The DOI matches its Crossref record; 26 of the 26 references it cites were found in a registry or an index; none of the 24 sources its claims cite is checked for support yet.
A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women
Open accessAbstract
Objective To evaluate the ovarian follicular dynamics of cycle modification with the aromatase inhibitor letrozole compared with clomiphene citrate in normal ovulatory women.Design Randomized double-blind controlled trial.Setting Tertiary care hospital.Patient(s) Nineteen ovulatory female volunteers, ages 18-35 years.Intervention(s) Subjects were monitored in one control cycle. Subjects then received either letrozole 2.5 mg daily or clomiphene citrate 50 mg daily on days 5-9 after menses.Main outcome measure(s) Number of mature follicles, endometrial thickness and endometrial pattern at ovulation, and follicular profiles of LH, FSH, and E(2).Result(s) The number of mature follicles at the LH surge in natural cycles was 1.0 with an exaggerated response seen for treatment both with clomiphene and letrozole. There was no difference in the endometrial thickness at midcycle during either the natural cycles or the medicated cycles. LH surges and spontaneous ovulation were documented in all natural and medicated cycles. When measured daily, follicular profiles of LH and FSH are similar between the groups in both the natural and medicated cycles. In the medicated cycles, clomiphene results in a significant increase in E(2) levels, while E(2) levels in letrozole-stimulated cycles appeared lower than in natural cycles.Conclusion(s) Transient inhibition of aromatase activity in the early follicular phase with the aromatase inhibitor letrozole results in stimulation of ovarian folliculogenesis similar to that seen with clomiphene citrate with no apparent adverse effect on endometrial thickness or pattern at midcycle.
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Written from the paper’s full text.
TL;DR
In a randomized double-blind pilot of normal ovulatory women, letrozole 2.5 mg/day and clomiphene citrate 50 mg/day on cycle days 5–9 both increased mature follicles at the LH surge compared with natural cycles, with comparable midcycle endometrial thickness and spontaneous ovulation. Letrozole produced lower E2 levels than clomiphene and natural cycles, but the authors conclude larger trials are needed.
Key findings
- Sixteen participants completed both cycles. The mean (±SD) number of mature follicles (≥18 mm) at the LH surge was 2.2 (±0.67) in the clomiphene-treated group and 1.7 (±0.49) in the letrozole-treated group (P=.11); natural-cycle values were 1.0 in both groups.
- Midcycle endometrial thickness was comparable: natural cycle 9.8 (±1.6) mm with clomiphene vs 9.9 (±2.4) mm with letrozole (P=.91); treatment cycle 10.1 (±2.2) mm vs 10.6 (±2.0) mm (P=.64). No within-group difference between natural and treated cycles.
- Tri-laminar endometrium at midcycle was present in 100% (9/9) of letrozole natural cycles vs 56% (5/9) of clomiphene natural cycles; in treatment cycles it was 71% with letrozole (P=.46) and 44% with clomiphene (P=1.00). LH surges and spontaneous ovulation were documented in all natural and medicated cycles.
- At the LH surge, mean (±SD) E2 was 686 (±388) pmol/L with clomiphene vs 560 (±193) pmol/L with letrozole in natural cycles, and 2,047 (±930) pmol/L vs 399 (±167) pmol/L in stimulated cycles; clomiphene significantly increased E2, while letrozole E2 appeared lower than natural cycles.
Methods
- Randomized double-blind controlled pilot at Kingston General Hospital, October 1999–April 2000. Nineteen normal ovulatory women ages 18–35 who did not desire pregnancy were enrolled; inclusion required day 3 FSH ≤10 IU/L, normal hormonal profile, and reliable contraception.
- Each participant was monitored through one natural cycle, then randomized to letrozole 2.5 mg/day or clomiphene citrate 50 mg/day on days 5–9 after menses. Monitoring included daily LH, FSH, and E2 and transvaginal ultrasound.
- Primary outcome was number of mature follicles (≥18 mm) at the LH surge; additional outcomes included follicular E2/LH/FSH profiles, endometrial thickness and pattern 1 day after the LH surge, and spontaneous ovulation. Analysis used Student’s t-test and Fisher’s exact test, with P<.05 significant.
Limitations
- The paper states that no a priori power calculation was possible because letrozole had never been administered to premenopausal women; it was a small pilot designed before a larger trial in infertility patients. The authors also state that daily blood sampling may have been too infrequent to detect brief LH/FSH increases, and that whether lower E2 in letrozole cycles affects implantation or luteal function is unknown.
- The paper states that a larger randomized trial is required to fully assess letrozole’s impact on endometrial development.
- Evident from the text: only 16 of 19 enrolled women completed both cycles and were analyzed, and participants were normal ovulatory volunteers rather than infertile patients, so findings may not generalize to infertility or polycystic ovary syndrome populations.
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Claims the paper makes
19 Own result · 15 Not checked yet · 10 Own method · 3 Own interpretation
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Early follicular treatment with clomiphene and letrozole resulted in a comparable increase in the number of mature follicles at the LH surge.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plaindirectn = 16- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In the treatment cycle, the mean (ϮSD) midcycle endometrial thickness was 10.1 mm (Ϯ2.2 mm) in the clomiphene group and 10.6 mm (Ϯ2.0 mm) in the letrozole group (Pϭ.64,Student's t-test).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Despite significantly lower E 2 levels in letrozole-treated women, endometrial development was unaffected in this study.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > DISCUSSION
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“During the natural cycle, the mean (ϮSD) E 2 levels on the day of the LH surge were 686 (Ϯ388) pmol/L for the clomiphene group and 560 (Ϯ193) pmol/L for the letrozole group.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“During the natural cycle, the mean (ϮSD) midcycle endometrial thickness in the clomiphene group was 9.8 mm (Ϯ1.6 mm) and in the letrozole group it was 9.9 mm (Ϯ2.4 mm; Pϭ.91, Student's t-test).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The number of mature follicles (Ն18 mm) at the LH surge in natural cycles was 1.0 in both the clomiphene and letrozole groups.”
- Also stated in: § Abstract · plain
“The number of mature follicles at the LH surge in natural cycles was 1.0 with an exaggerated response seen for treatment both with clomiphene and letrozole.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plainn = 16- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Also stated in: § Abstract · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Within each group, there was no difference in the mean endometrial thickness between the natural and treated cycles.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“There was no significant reduction in the number of women with a midcycle tri-laminar pattern in either group during the treatment cycle (letrozole 71%, Pϭ.46, Fisher's exact test; and clomiphene 44%, Pϭ1.00, Fisher's exact test).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Endometrial thickness at midcycle was comparable between the groups during both natural cycles and treatment cycles.”
- Also stated in: § Abstract · plain
“There was no difference in the endometrial thickness at midcycle during either the natural cycles or the medicated cycles.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plainn = 19- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Also stated in: § Abstract · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In the stimulated cycle, the mean (ϮSD) E 2 levels on the day of the LH surge were 2,047 (Ϯ930) pmol/L for the clomiphene group and 399 (Ϯ167) pmol/L for the letrozole group.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- It may state two separate claims as one. 13
- Probably not a substantial claim. 13
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“When expressed as E 2 produced per follicle, clomiphene resulted in a slight increase in E 2 level per follicle, while letrozole resulted in a slight decrease in E 2 level per follicle compared with natural cycles (Fig. 4).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The mean (ϮSD) number of mature follicles in the clomiphene-treated group was 2.2 (Ϯ0.67), while that in the letrozole-treated group was 1.7 (Ϯ0.49) (Pϭ.11,Student's t-test).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plainn = 16- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In the medicated cycles, clomiphene resulted in a significant increase in E 2 levels, while letrozole resulted in E 2 levels lower than those in natural cycles.”
- Also stated in: § Abstract · hedged
“In the medicated cycles, clomiphene results in a significant increase in E 2 levels, while E 2 levels in letrozole-stimulated cycles appeared lower than in natural cycles.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plaindirectn = 19- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Also stated in: § Abstract · hedged
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“While all women in the letrozole group had tri-laminar pattern endometrium at midcycle in the natural cycle (100%), only 56% (5/9) of those in the clomiphene group had a tri-laminar pattern in the natural cycle.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“LH surges and spontaneous ovulation were documented in all natural and medicated cycles.”
- Also stated in: § RESULTS · plain
“LH surges and spontaneous ovulation were documented in all natural and medicated cycles.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > Abstract
plainn = 19- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Also stated in: § RESULTS · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Of three women with a thin endometrium at midcycle in the treatment cycle, two women had received clomiphene (8 and 7.3 mm) and one had received letrozole (7.6 mm).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plainn = 3- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Of interest, all of the women with a thin endometrium during the treatment cycle had greater endometrial thickness in the natural cycle (clomiphene group, 9.5 and 11.7 mm; letrozole group, 8.7 mm).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plaincorrelationaln = 3- Asserted: passes — The authors put it forward as true.
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- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
None of the sources cited for this claim have been checked yet.
In the paper
“Clomiphene results in a 60%-85% ovulation rate and a 10%-20% pregnancy rate per cycle (2)(3)(4)(5)(6)(7)(8).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > Abstract
What the sources say
- Not checked yetcites [2] Dickey, 1996, Incidence of spontaneous abortion in clomiphene pregnancies, Hum Reprod source
- Not checked yetcites [3] Garcia, 1977, The use of clomiphene citrate, Fertil Steril source
- Not checked yetcites [4] Gorlitsky, 1978, Ovulation and pregnancy rates with clomiphene citrate, Obstet Gynecol source
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
In the paper
“Clomiphene citrate has been widely used in the treatment of infertility since its introduction into clinical practice in the 1960s (1).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > Abstract
What the sources say
- Not checked yetcites [1] Greenblatt, 1961, Induction of ovulation with MRL/41, JAMA source
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
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Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“and a significantly higher rate of biochemical pregnancies when the endometrial thickness was 6 -8 mm (15).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > Abstract
What the sources say
- Not checked yetcites [15] Dickey, 1993, Relationship of biochemical pregnancy to preovulatory endometrial thickness and pattern in ovulation induction patients, Hum Reprod source
plaincorrelational- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“Letrozole (Femara; Novartis Pharmaceuticals, Dorval, Que ´bec, Canada) is a potent, reversible oral aromatase inhibitor that has recently been tested in phase 3 trials as a chemotherapeutic agent in postmenopausal women with metastatic breast cancer (17).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > Abstract
What the sources say
- Not checked yetcites [17] Lamb, 1998, Letrozole, Drugs source
plain- Asserted: passes — The authors put it forward as true.
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- Load-bearing: fails — The paper’s conclusions may not depend on it.
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Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The Queen's University Health Sciences and Affiliated Teaching Hospitals Research Ethics Board approved the study protocol.Study participants were counseled, and informed consent was obtained before randomization.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > MATERIALS AND METHODS
plain- Asserted: passes — The authors put it forward as true.
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- Load-bearing: fails — The paper’s conclusions may not depend on it.
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Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“A total of 16 participants completed both cycles of the study and were included in the final analysis of data.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plainn = 16- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“This pilot study was performed as a randomized doubleblind controlled investigation between October, 1999 and April, 2000 at Kingston General Hospital, Kingston, Ontario.”
- Also stated in: § Abstract · plain
“Design: Randomized double-blind controlled trial.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > MATERIALS AND METHODS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
- Also stated in: § Abstract · plain
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“Randomization was performed by choosing the next sequentially numbered opaque envelope prepared by the hospital pharmacy according to random number tables with randomization in blocks of four.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > MATERIALS AND METHODS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Transient inhibition of aromatase activity in the early follicular phase with the aromatase inhibitor letrozole results in stimulation of ovarian folliculogenesis similar to that seen with clomiphene citrate with no apparent adverse effect on endometrial thickness or pattern at midcycle.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > Abstract
hedgeddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
In the paper
“A single daily dose of 2.5 mg/day has been shown to achieve optimal suppression of serum estrogen levels in postmenopausal women (18).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > Abstract
What the sources say
- Not checked yetcites [18] Dowsett, 1995, In vivo measurement of aromatase inhibition by letrozole (CGS 20267) in postmenopausal women with breast cancer, Clin Cancer Res
boosteddirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“One woman from the clomiphene group voluntarily withdrew from the study after completing the control cycle.Two women from the letrozole group failed to complete the study: 1 woman failed to ovulate in the control cycle and was withdrawn after randomization, and 1 woman voluntarily withdrew from the study before completion of the control cycle for personal reasons.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > RESULTS
plainn = 2- Asserted: passes — The authors put it forward as true.
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- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“To accomplish blinding of the medications, the required daily doses of both letrozole and clomiphene were prepared by the hospital pharmacy in identical capsule form before randomization.Study investigators, radiologists, ultrasound technicians, and participants were unaware of study group allocation.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > MATERIALS AND METHODS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. It may state two separate claims as one.
In the paper
“When administered to normally cycling female rats, letrozole resulted in greater than 80% suppression of ovarian E 2 levels and caused a marked increase in LH and FSH, with a 35% increase in ovarian weights within 1 week of treatment (19).”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > Abstract
What the sources say
- Not checked yetcites [19] Sinha, 1998, Effect of CGS 20267 on ovarian aromatase and gonadotropin levels in the rat, Breast Cancer Res Treat source
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“At the beginning of this study, letrozole had never been administered to premenopausal women, and neither the dose required to achieve suppression of ovarian aromatase nor the clinical effect of the chosen dose could be predicted.This precluded an a priori power calculation.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > MATERIALS AND METHODS
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“Samples from the control and stimulation cycle of each subject were always assayed in the same LH and FSH assay.”
§ A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women > MATERIALS AND METHODS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
The paper relies on this without support.
Letrozole does not cause estrogen receptor depletion.
“Because letrozole is more rapidly eliminated than clomiphene and does not cause estrogen receptor depletion, it is likely that letrozole may not cause the adverse endometrial effects observed with clomiphene, ultimately resulting in improved pregnancy rates.”
The paper relies on this without support.
Letrozole is more rapidly eliminated than clomiphene.
“Because letrozole is more rapidly eliminated than clomiphene and does not cause estrogen receptor depletion, it is likely that letrozole may not cause the adverse endometrial effects observed with clomiphene, ultimately resulting in improved pregnancy rates.”
The paper relies on this without support.
Clomiphene citrate is the current standard oral treatment for ovulation induction.
“The efficacy of letrozole was compared with clomiphene citrate, rather than placebo, to establish its equivalence to the current standard oral treatment for ovulation induction.”
The paper relies on this without support.
Normal ovulatory women are an appropriate model for evaluating letrozole before testing it in infertile women.
“This small pilot study was designed to evaluate the potential of letrozole as an ovulation induction agent before embarking on a larger trial involving infertility patients.”
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“In superovulation, letrozole is associated with few developing follicles and thick endometrium.”
From A new era in ovulation induction (2006) · cites this paper as [53]
Citations
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Goodman, N. F., Cobin, R. H., Futterweit, W., Glueck, J. S., Legro, R. S., & Carmina, E. (2015) · Endocrine Practice · doi:10.4158/ep15748.dscpt2 · Cited by 366
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Homburg, R. (2005) · Human Reproduction · doi:10.1093/humrep/dei042 · Cited by 332
“A direct comparison of letrozole with 50mg/day of CC in ovulatory women in an RCT showed similar effects on stimulation of folliculogenesis, whilst endometrial thickness was maintained by letrozole despite much lower estradiol concentrations than with CC at mid-cycle (Fisher et al., 2002).”
BackgroundAromatase Inhibitors for Ovulation Induction
Casper, R. F., & Mitwally, M. F. (2006) · The Journal of Clinical Endocrinology & Metabolism · doi:10.1210/jc.2005-1923 · Cited by 272
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“Nevertheless, aromatase inhibitor drugs have recently been used in ovulation induction (Fisher et al., 2002), and we are conducting a prospective study to test their value for fertility preservation in breast cancer patients as they may not result in a rise in estradiol levels.”
BackgroundClomiphene citrate versus letrozole for ovarian stimulation: a pilot study
Fatemi, H. M., Kolibianakis, E. M., Tournaye, H. J., Camus, M., Steirteghem, A. V., & Devroey, P. (2003) · Reproductive BioMedicine Online · doi:10.1016/s1472-6483(10)62070-6 · Cited by 253
“In a randomized study, Fisher et al. (2002) compared the administration of CC and letrozole for IUI.”
BackgroundSmith, I. E., Dowsett, M., Yap, Y. S., Walsh, G., Lønning, P. E., Santen, R. J., & Hayes, D. F. (2006) · Journal of Clinical Oncology · doi:10.1200/jco.2005.05.3694 · Cited by 203
Use of letrozole in assisted reproduction: a systematic review and meta-analysis
Requena, A., Herrero, J. C., Landeras, J., Navarro, E., Neyro, J. L., Salvador, C., Tur, R., Callejo, J., Checa, M. Á., Farré, M., et al. (2008) · Human Reproduction Update · doi:10.1093/humupd/dmn033 · Cited by 197
“Augmenting endogenous FSH with CC treatment is associated with a risk of ovarian hyperstimulation syndrome and multiple gestations (Fisher et al., 2002).”
BackgroundA new era in ovulation induction
Holzer, H., Casper, R., & Tulandi, T. (2006) · Fertility and Sterility · doi:10.1016/j.fertnstert.2005.05.078 · Cited by 194
Self-citationAromatase inhibitors: the next generation of therapeutics for endometriosis?
Attar, E., & Bulun, S. E. (2006) · Fertility and Sterility · doi:10.1016/j.fertnstert.2005.09.064 · Cited by 184
The physiology of follicle selection
Zeleznik, A. J. (2004) · Reproductive Biology and Endocrinology · doi:10.1186/1477-7827-2-31 · Cited by 148
Badawy, A., Aal, I. A., & Abulatta, M. (2007) · Fertility and Sterility · doi:10.1016/j.fertnstert.2007.02.062 · Cited by 133
RetractedUse of clomiphene citrate in infertile women: a committee opinion
(2013) · Fertility and Sterility · doi:10.1016/j.fertnstert.2013.05.033 · Cited by 124
Polycystic ovary syndrome and infertility: an update
Zehravi, M., Maqbool, M., & Ara, I. (2021) · International Journal of Adolescent Medicine and Health · doi:10.1515/ijamh-2021-0073 · Cited by 124
Begum, M. R., Ferdous, J., Begum, A., & Quadir, E. (2008) · Fertility and Sterility · doi:10.1016/j.fertnstert.2007.08.044 · Cited by 109
Kar, S. (2012) · Journal of Human Reproductive Sciences · doi:10.4103/0974-1208.106338 · Cited by 108
“Few studies have shown no significant difference between the two groups with regard to effect on endometrium.[27,28] In a recent study by Banerjee et al.”
BackgroundCasper, R. F., & Mitwally, M. F. (2011) · Clinical Obstetrics & Gynecology · doi:10.1097/grf.0b013e3182353d0f · Cited by 99
Self-citationSohrabvand, F., Ansari, S., & Bagheri, M. (2006) · Human Reproduction · doi:10.1093/humrep/del020 · Cited by 97
“It is probable that the cause of endometrial thickening in patients receiving letrozole is because of improved vascularization as compared with clomiphene citrate (Fisher et al., 2002).”
BackgroundInfluentialFertility Preservation in Women With Breast Cancer
Rodriguez‐Wallberg, K. A., & Oktay, K. (2010) · Clinical Obstetrics & Gynecology · doi:10.1097/grf.0b013e3181f96e00 · Cited by 96
“Use of letrozole alone for ovarian stimulation has been associatedwith lower estrogen levels than those of the natural cycle.(27) Data on the use of anastrozole for ovarian stimulation in anovulatory women, however, is more limited and studies so far do not support its use over clomiphene.”
BackgroundLetrozole vs. clomiphene citrate in patients with ovulatory infertility
Bayar, Ü., Tanriverdi, H. A., Barut, A., Ayoğlu, F. N., Özcan, O., & Kaya, E. (2006) · Fertility and Sterility · doi:10.1016/j.fertnstert.2005.09.045 · Cited by 93
Cortínez, A., Carvalho, I. D., Vantman, D., Gabler, F., Íñiguez, G., & Vega, M. (2005) · Fertility and Sterility · doi:10.1016/j.fertnstert.2004.05.099 · Cited by 92
Roy, K., Baruah, J., Singla, S., Sharma, J., Singh, N., Jain, S. K., & Goyal, M. (2012) · Journal of Human Reproductive Sciences · doi:10.4103/0974-1208.97789 · Cited by 95
“It is known that clomiphene citrate results in an ovulation rate of 60–85% but a conception rate of only about 20%.[2] CC has a long half-life (2 weeks), and this may have a negative effect on the cervical mucus and endometrium, leading to discrepancy between ovulation and conception rates.”
Successful treatment of severe endometriosis in two premenopausal women with an aromatase inhibitor
Shippen, E., & West, W. J. (2004) · Fertility and Sterility · doi:10.1016/j.fertnstert.2003.11.027 · Cited by 85
A randomized trial of superovulation with two different doses of letrozole
Al-Fadhli, R., Sylvestre, C. V., Buckett, W. M., Tan, S. L., & Tulandi, T. (2006) · Fertility and Sterility · doi:10.1016/j.fertnstert.2005.07.1283 · Cited by 84
Use of aromatase inhibitors in poor-responder patients receiving GnRH antagonist protocols
Özmen, B., Sönmezer, M., Atabekoğlu, C. S., & Olmuş, H. (2009) · Reproductive BioMedicine Online · doi:10.1016/j.rbmo.2009.05.007 · Cited by 82
“It was reported that transient inhibition of aromatase activity in early follicular phase (on days 5–9) with letrozole results in ovarian stimulation similar to clomiphene citrate with no apparent adverse effect on endometrium (Fisher et al., 2002). Mitwally and Casper (2003) also supported that letrozole is effective…”
BackgroundTreatment strategies for endometriosis
Rodgers, A. K., & Falcone, T. (2008) · Expert Opinion on Pharmacotherapy · doi:10.1517/14656566.9.2.243 · Cited by 72
“They are given cyclically for infertility compared with continuously if used for pain [73-76] .”
BackgroundLetrozole for ovulation induction and controlled ovarian hyperstimulation
Pritts, E. A. (2010) · Current Opinion in Obstetrics & Gynecology · doi:10.1097/gco.0b013e32833beebf · Cited by 76
Ebert, A. D., Bartley, J., & David, M. (2005) · European Journal of Obstetrics & Gynecology and Reproductive Biology · doi:10.1016/j.ejogrb.2005.04.017 · Cited by 73
Aromatase inhibitors in ovarian stimulation
Casper, R. F. (2007) · The Journal of Steroid Biochemistry and Molecular Biology · doi:10.1016/j.jsbmb.2007.05.025 · Cited by 68
Self-citationOvulation induction in women with polycystic ovary syndrome
Perales‐Puchalt, A., & Legro, R. S. (2013) · Steroids · doi:10.1016/j.steroids.2013.05.005 · Cited by 66
“However, clinical trials have failed to find a difference in endometrial thickness comparing women receiving letrozole or clomiphene with non-stimulated cycles [52,53].”
BackgroundÖner, G., Özçelik, B., Özgün, M. T., Serin, İ. S., Öztürk, F., & Başbuğ, M. (2010) · Human Reproduction · doi:10.1093/humrep/deq016 · Cited by 66
“Letrozole is also used for ovulation induction and superior to clomiphene citrate (CC) when comparing side effects, ovulation and pregnancy rates in a general infertile population (Mitwally and Casper, 2001; Fisher et al., 2002; Lord et al., 2003; Atay et al., 2006).”
BackgroundStrategies to reduce multiple pregnancies due to ovulation stimulation
Dickey, R. P. (2008) · Fertility and Sterility · doi:10.1016/j.fertnstert.2008.08.008 · Cited by 66
Biomaterials for Dental Implants: An Overview
Amarnath, G. S., Muddugangadhar, B. C., Tripathi, S., Suchismita, D., & Divya, M. S. (2011) · International Journal of Oral Implantology and Clinical Research · doi:10.5005/jp-journals-10012-1030 · Cited by 62
Baruah, J., Roy, K. K., Rahman, S. M., Kumar, S., Sharma, J. B., & Karmakar, D. (2008) · Archives of Gynecology and Obstetrics · doi:10.1007/s00404-008-0714-4 · Cited by 59
PCOS: an ovarian disorder that leads to dysregulation in the hypothalamic–pituitary–adrenal axis?
Doi, S. A. R., Towers, P. A., Scott, C., & Al-Shoumer, K. A. S. (2004) · European Journal of Obstetrics & Gynecology and Reproductive Biology · doi:10.1016/j.ejogrb.2004.06.024 · Cited by 57
Irregular cycles and steroid hormones in polycystic ovary syndrome
Doi, S. A. R., Al-Zaid, M. M., Towers, P. A., Scott, C., & Al-Shoumer, K. A. S. (2005) · Human Reproduction · doi:10.1093/humrep/dei093 · Cited by 55
“However, even obese women had the same differential between groups 1 and 2 as lean women, adding to the robustness of these results.”
BackgroundResultHu, Y., Chen, Y., Zhu, Y., & Huang, H. (2013) · Clinical Endocrinology · doi:10.1111/cen.12280 · Cited by 52
Ray, P. B., Ray, A., & Chakraborti, P. S. (2011) · Archives of Gynecology and Obstetrics · doi:10.1007/s00404-011-2091-7 · Cited by 54
Okman, T. K., Küçük, M., & Altaner, Ş. (2003) · Fertility and Sterility · doi:10.1016/j.fertnstert.2003.05.002 · Cited by 50
Abdellah, M. S. (2011) · International Journal of Gynecology & Obstetrics · doi:10.1016/j.ijgo.2010.11.026 · Cited by 41
“Patients receiving letrozole probably have a thicker endometrium because the vascularization is improved [24].”
BackgroundRetractedKenealy, B. P., Keen, K. L., Garcia, J. P., Kohlenberg, L. K., & Terasawa, E. (2017) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1716097115 · Cited by 37
Use of clomiphene citrate in women
(2006) · Fertility and Sterility · doi:10.1016/j.fertnstert.2006.08.023 · Cited by 41
Jirge, P. R., & Patil, R. S. (2008) · Fertility and Sterility · doi:10.1016/j.fertnstert.2008.10.009 · Cited by 39
“The findings of this study also support the previous evidence that multifollicular ovulation is less marked with LE than CC treatment (15).”
BackgroundResultEruption Chronology in Children: A Cross-sectional Study
Verma, N., Bansal, A., Tyagi, P., Jain, A., Tiwari, U., & Gupta, R. (2017) · International Journal of Clinical Pediatric Dentistry · doi:10.5005/jp-journals-10005-1450 · Cited by 40
Schwartz, A. R., Russell, K., & Gray, B. (2019) · Obstetrics and Gynecology · doi:10.1097/aog.0000000000003308 · Cited by 38
Nejad, E. S. T., Abediasl, Z., Rashidi, B. H., Nekoo, E. A., Shariat, M., & Amirchaghmaghi, E. (2008) · Journal of Assisted Reproduction and Genetics · doi:10.1007/s10815-008-9209-2 · Cited by 37
“Another study also showed that clomiphene citrate can cause inadequate endometrial thickness in 15–50% of patients and have negative effects on the quality or quality of the cervical and endometrial mucosa [22].”
BackgroundSurface Modifications for Endosseous Dental Implants
Shetty, O. K., Parekh, R., & Tabassum, R. (2012) · International Journal of Oral Implantology and Clinical Research · doi:10.5005/jp-journals-10012-1078 · Cited by 38
ACOG Committee Opinion No. 738: Aromatase Inhibitors in Gynecologic Practice
(2018) · Obstetrics and Gynecology · doi:10.1097/aog.0000000000002640 · Cited by 36
Patient-tailored conventional ovulation induction algorithms in anovulatory infertility
van Santbrink, E. J. P., Eijkemans, M. J. C., Laven, J. S. E., & Fauser, B. C. J. M. (2005) · Trends in Endocrinology and Metabolism · doi:10.1016/j.tem.2005.08.006 · Cited by 36
Tredway, D. R., Buraglio, M., Hemsey, G., & Denton, G. (2004) · Fertility and Sterility · doi:10.1016/j.fertnstert.2004.04.059 · Cited by 35
Thakur, S., & Habib, R. (2017) · International Journal of Clinical Pediatric Dentistry · doi:10.5005/jp-journals-10005-1442 · Cited by 33
Seyedoshohadaei, F. (2016) · JOURNAL OF CLINICAL AND DIAGNOSTIC RESEARCH · doi:10.7860/jcdr/2016/20954.8324 · Cited by 33
Letrozole versus human menopausal gonadotrophin in women undergoing intrauterine insemination
Baysoy, A., Serdaroğlu, H., Jamal, H., Karatekeli, E., Özörnek, H., & Attar, E. (2006) · Reproductive BioMedicine Online · doi:10.1016/s1472-6483(10)60617-7 · Cited by 33
van Santbrink, E. J. P., Hohmann, F. P., Eijkemans, M. J. C., Laven, J. S. E., & Fauser, B. C. J. M. (2005) · European Journal of Endocrinology · doi:10.1530/eje.1.01866 · Cited by 31
Montville, C. P., Khabbaz, M., Aubuchon, M., Williams, D. B., & Thomas, M. A. (2009) · Fertility and Sterility · doi:10.1016/j.fertnstert.2009.03.088 · Cited by 30
Quintero, R. B., Urban, R. R., Lathi, R. B., Westphal, L. M., & Dahan, M. H. (2007) · Fertility and Sterility · doi:10.1016/j.fertnstert.2006.11.166 · Cited by 30
Seyedoshohadaei, F., Zandvakili, F., & Shahgeibi, S. (2012) · Europe PMC (PubMed Central) · Cited by 30
Ovulation induction in normogonadotropic anovulation (PCOS)
van Santbrink, E. J. P., & Fauser, B. C. J. M. (2006) · Best Practice & Research Clinical Endocrinology & Metabolism · doi:10.1016/j.beem.2006.03.002 · Cited by 30
Selim, M. F., & Borg, T. F. (2012) · Journal of Gynecologic Surgery · doi:10.1089/gyn.2012.0033 · Cited by 29
“18,19 Baruah et al. 12 concluded that the effect of letrozole on endometrial thickness in patients with anovulatory PCOS was significantly better compared to CC.”
Wu, H., Wang, N. M., Cheng, M.-L., & Hsieh, J.-N. (2007) · Gynecological Endocrinology · doi:10.1080/09513590601137509 · Cited by 29
“In the study of Fisher and colleagues [6], the profiles of LH and FSH were similar in medicated cycles with clomiphene and letrozole.”
BackgroundResultIs ovulation induction still a therapeutic problem in patients with polycystic ovary syndrome?
Palomba, S., Orio, F., Russo, T., Falbo, A. I., Cascella, T., Colao, A. A. L., Lombardi, G., & Zullo, F. (2004) · Journal of Endocrinological Investigation · doi:10.1007/bf03347527 · Cited by 29
Evolution of External and Internal Implant to Abutment Connection
Prithviraj, D., & Muley, N. (2012) · International Journal of Oral Implantology and Clinical Research · doi:10.5005/jp-journals-10012-1079 · Cited by 27
Prajapati, D., Nayak, R., Pai, D., Upadhya, N., Bhaskar, V., & Kamath, P. (2017) · International Journal of Clinical Pediatric Dentistry · doi:10.5005/jp-journals-10005-1445 · Cited by 27
Suma, N. (2017) · International Journal of Clinical Pediatric Dentistry · doi:10.5005/jp-journals-10005-1440 · Cited by 25
A bovine model for examining the effects of an aromatase inhibitor on ovarian function in women
Yapura, J., Mapletoft, R. J., Pierson, R. A., Singh, J. K., Naile, J. E., Giesy, J. P., & Adams, G. P. (2011) · Fertility and Sterility · doi:10.1016/j.fertnstert.2011.05.038 · Cited by 25
Mehdinejadiani, S., Amidi, F., Mehdizadeh, M., Barati, M., Safdarian, L., Aflatoonian, R., Alyasin, A., Aghahosseini, M., Pazhohan, A., Hayat, P., et al. (2018) · Gynecological Endocrinology · doi:10.1080/09513590.2018.1446934 · Cited by 24
“Many studies had compared the effects CC and letrozole on pregnancy outcome; it found the obvious difference between the ovulation and pregnancy rate in using CC [13,14] which may be explained by the side effects of CC, particularly, the peripheral anti-estrogenic action on the cervix and endometrium.”
Background(2016) · Obstetrics and Gynecology · doi:10.1097/aog.0000000000001484 · Cited by 24
Begum, M. R., Quadir, E., Begum, A., Begum, R. A., & Begum, M. (2006) · Journal of obstetrics and gynaecology research · doi:10.1111/j.1447-0756.2006.00434.x · Cited by 23
“They showed 75% and 100% ovulation, respectively, when they used 2.5 mg letrozole/day in anovulatory and ovulatory patients by CC.11,22,23 In our series the ovulation rate was 100% with 2.5 mg and 88.46% with 5 mg. Patients who were not responsive at all to 150 mg CC per day did not develop mature follicles even with…”
BackgroundInfluentialSipe, C. S., Davis, W. A., Maifeld, M., & Voorhis, B. J. V. (2006) · Fertility and Sterility · doi:10.1016/j.fertnstert.2006.05.048 · Cited by 24
Clinical use of aromatase inhibitors (AI) in premenopausal women
de Ziegler, D., Mattenberger, C., Luyet, C., Romoscanu, I., Irion, N. F., & Bianchi-Demicheli, F. (2005) · The Journal of Steroid Biochemistry and Molecular Biology · doi:10.1016/j.jsbmb.2005.04.023 · Cited by 24
RetractedTredway, D. R., Schertz, J. C., Bock, D., Hemsey, G., & Diamond, M. P. (2011) · Fertility and Sterility · doi:10.1016/j.fertnstert.2010.12.064 · Cited by 23
Samani, F. G., Farzadi, L., Nezami, N., Tarzamni, M. K., & Soleimani, F. (2008) · Archives of Gynecology and Obstetrics · doi:10.1007/s00404-008-0888-9 · Cited by 23
“Although in the Fisher et al. study [ 28 ], the proWles for LH were not statistically diVerent in medicated cycles with CC and LET, some studies conducted after Fisher et al. [28] entirely showed that LH level during LET cycle was higher than CC [19, 23, 30, 40].”
ResultGynecologic and hormonal effects of raloxifene in premenopausal women
Premkumar, A., Venzon, D. J., Avila, N. A., Johnson, D. V., Remaley, A. T., Forman, M. R., Eng‐Wong, J., Zujewski, J. A., & Stratton, P. (2007) · Fertility and Sterility · doi:10.1016/j.fertnstert.2007.01.095 · Cited by 23
Pourali, L., Ayati, S., Tavakolizadeh, S., Soleimani, H., & Sani, F. T. (2017) · International Journal of Reproductive BioMedicine (IJRM) · doi:10.29252/ijrm.15.1.49 · Cited by 23
de Ziegler, D. (2003) · Human Reproduction · doi:10.1093/humrep/deg310 · Cited by 22
A Review on the Use of Letrozole in Female and Male Infertility
Pajai, S., Potdar, J., Gopal, U., & Banait, T. (2022) · Cureus · doi:10.7759/cureus.31291 · Cited by 21
“This extended regimen inhibits aromatization for a longer duration, which keeps the synthesis of FSH continuous for a longer duration and thereby gives satisfactory ovulation rates [24].”
BackgroundThe effects of metformin and letrozole on endometrium and ovary in a rat model
Öner, G., Özçelik, B., Özgün, M. T., & Öztürk, F. (2011) · Gynecological Endocrinology · doi:10.3109/09513590.2011.589928 · Cited by 21
“The cause of endometrial thickening in patients receiving letrozole is because of improved vascularization [20].”
BackgroundDas, D., Samir, P. V., Verma, R. K., & Singh, N. (2017) · International Journal of Clinical Pediatric Dentistry · doi:10.5005/jp-journals-10005-1448 · Cited by 21
Bedaiwy, M. A., Mousa, N. A., Esfandiari, N., Forman, R., & Casper, R. F. (2006) · The Journal of Clinical Endocrinology & Metabolism · doi:10.1210/jc.2006-1673 · Cited by 21
“(17), in a randomized double-blind controlled trial, found that the E2 levels in letrozole-stimulated cycles appeared lower than in natural cycles or CC cycles.”
BackgroundSelf-citationDavar, R., Javedani, M., & Fallahzadeh, M. H. (2011) · PubMed Central · Cited by 20
Is the use of letrozole to induce ovulation teratogenic?
Gill, S. K., Moretti, M. E., & Koren, G. (2008) · PubMed Central · Cited by 20
Anatomical Considerations in Implant Selection and Positioning
Shetty, M., Prasad, K., & Mehra, D. (2013) · International Journal of Oral Implantology and Clinical Research · doi:10.5005/jp-journals-10012-1088 · Cited by 19
Abizadeh, M., Novin, M. G., Amidi, F., Ziaei, S. A., Abdollahifar, M., & Nazarian, H. (2020) · Reproductive Sciences · doi:10.1007/s43032-020-00168-9 · Cited by 19
“However, resistance to clomiphene citrate remains a big problem [10, 11].”
BackgroundUse of clomiphene citrate in women
The Practice Committee of the American Society for Reproductive Medicine (2003) · Fertility and Sterility · doi:10.1016/s0015-0282(03)01184-1 · Cited by 19
Elassar, A. A., Engmann, L., NULSEN, J. C., & Benadiva, C. A. (2011) · Fertility and Sterility · doi:10.1016/j.fertnstert.2011.03.103 · Cited by 19
Liu, W., Dong, S., Li, Y., Shi, L., Zhou, W., Liu, Y., Liu, J., & Ji, Y. (2015) · Experimental and Therapeutic Medicine · doi:10.3892/etm.2015.2690 · Cited by 19
“Several studies have been conducted regarding the treatment of CC-resistant PCOS with LE or LOD, and positive results have been achieved; however, there have been few studies comparing the effects of the two treatments (21-23).”
Polyetheretherketone (PEEK) Dental Implants: A Case for Immediate Loading
Marya, K., Dua, J., Chawla, S., Sonoo, P. R., Aggarwal, A., & Singh, V. (2011) · International Journal of Oral Implantology and Clinical Research · doi:10.5005/jp-journals-10012-1043 · Cited by 18
A randomized trial comparing the ovulation induction efficacy of clomiphene citrate and letrozole
Ghose, S., Gowda, M. S. S., & Angel, M. (2014) · Journal of Natural Science Biology and Medicine · doi:10.4103/0976-9668.136241 · Cited by 16
“Concurrent to previous reports[6,10] we observed a significantly higher serum estradiol levels in clomiphene citrate-treated group.”
BackgroundResultInfluentialEffects of a non-steroidal aromatase inhibitor on ovarian function in cattle
Yapura, J., Mapletoft, R. J., Singh, J. K., Pierson, R. A., Naile, J. E., Giesy, J. P., Chang, H., Higley, E. B., Hecker, M., & Adams, G. P. (2011) · Reproduction Fertility and Development · doi:10.1071/rd11239 · Cited by 16
“Letrozole has been used alone as a single or a 5-day regimen for ovarian stimulation [42, 130, 131], and in higher or increasing doses to induce”
BackgroundMethodHarira, M. M. (2018) · Middle East Fertility Society Journal · doi:10.1016/j.mefs.2018.05.008 · Cited by 15
Kotsakis, G. A., Chrepa, V., & Katta, S. (2011) · International Journal of Oral Implantology and Clinical Research · doi:10.5005/jp-journals-10012-1051 · Cited by 15
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Peddi, R., Sunitha, B., & Tarasingh, P. (2017) · International Journal of Clinical Pediatric Dentistry · doi:10.5005/jp-journals-10005-1443 · Cited by 15
Gonshor, A., Saroff, S. A., Anderegg, C. R., Joachim, F., Charon, J. A., Prasad, H., & Katta, S. (2011) · International Journal of Oral Implantology and Clinical Research · doi:10.5005/jp-journals-10012-1040 · Cited by 14
Aromatase inhibitor strategies in metastatic breast cancer
McArthur, H. L. (2009) · International Journal of Women s Health · doi:10.2147/ijwh.s4217 · Cited by 14
Chaudhary, I., & Tripathi, A. M. (2017) · International Journal of Clinical Pediatric Dentistry · doi:10.5005/jp-journals-10005-1447 · Cited by 14
Mesial Stripping of Mandibular Deciduous Canines for Correction of Permanent Lateral Incisors
Nakhjavani, Y. B., Nakhjavani, F. B., & Jafari, A. (2017) · International Journal of Clinical Pediatric Dentistry · doi:10.5005/jp-journals-10005-1441 · Cited by 13
Laser: Tissue Interaction and Its Application in Clinical Dentistry
Parker, S. P. A. (2011) · International Journal of Laser Dentistry · doi:10.5005/jp-journals-10022-1001 · Cited by 13
Management of Infertility in Women with Polycystic Ovary Syndrome
Stadtmauer, L., & Oehninger, S. (2005) · Treatments in Endocrinology · doi:10.2165/00024677-200504050-00002 · Cited by 13
Improving ovarian stimulation protocols for IVF in baboons: Lessons from humans and rhesus monkeys
Nyachieo, A., Spiessens, C., Mwenda, J. M., Debrock, S., & D’Hooghe, T. (2008) · Animal Reproduction Science · doi:10.1016/j.anireprosci.2008.08.023 · Cited by 11
Metadata
- Authors
- Fisher, S. A., Reid, R. L., Van Vugt, D. A., & Casper, R. F.
- Affiliations
- Queen's University (CA)
- University of Toronto (CA)
- Corresponding author
- Reid, Robert L
- Venue
- Fertility and Sterility
- Publisher
- Elsevier BV
- Published
- 2002-08
- Volume
- 78
- Issue
- 2
- Pages
- 280-285
- ISSN
- 0015-0282 (ISSN-L)
- OpenAlex
- W2029278810
- Semantic Scholar
- 1a3a5d4d0b6f3798f147b32266da94b97f987fe1
- Cited by
- 347
- References
- 26
- Citations by year
- 2025: 2 · 2024: 4 · 2023: 2 · 2022: 2 · 2021: 5 · 2020: 4 · 2019: 5 · 2018: 6 · 2017: 37 · 2016: 8 · 2015: 41 · 2014: 35 · 2013: 28 · 2012: 38
- FWCI
- 8.74
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- Locations
- Fertility and Sterility (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Health Sciences › Medicine › Reproductive Medicine › Ovarian function and disorders
- Health Sciences › Medicine › Reproductive Medicine › Reproductive Biology and Fertility
- Health Sciences › Medicine › Reproductive Medicine › Reproductive Health and Technologies
- Keywords
- clomiphene citrate, letrozole, aromatase inhibitors, ovulation induction, ovarian follicle development, endometrial thickness, luteinizing hormone surge, follicle-stimulating hormone, estradiol
- MeSH terms
- Letrozole, Adolescent, Adult, Clomiphene, Double-Blind Method, Estrogen Antagonists, Fertility Agents, Female, Follicle Stimulating Hormone, Humans, Middle Aged, Nitriles, Ovulation, Pilot Projects, Triazoles, Aromatase Inhibitors
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