Peripheral biomarkers of endometriosis: a systematic review

In the citing paper

“Firstly, according to QUADAS (Quality Assessment of Diagnostic Accuracy Studies) guidelines [15,16], samples should be collected at a consistent phase of the cycle and results should be corrected for the cycle phases.”

In the citing paper

“Secondly, according to a recently published systematic review, lack of correction for the phase of the menstrual cycle can explain the considerable variability between studies with respect to blood levels of biomarkers in women with endometriosis and controls [15].”

In the citing paper

“Studies performed in various compartments in the body as serum, peritoneal, and follicular fluids are not sufficient for precise evaluation [17].”

In the citing paper

“In our study, samples were collected at a well defined phase of the cycle and results were corrected for cycle phase, as recommended by the QUADAS (Quality Assessment of Diagnostic Accuracy Studies) guidelines [15,16].”

In the citing paper

“Despite the fact that research on biomarkers of endometriosis are still ongoing, there are still no satisfactory results, which makes it impossible to carry out effective laboratory diagnostics used in the diagnosis and monitoring of the treatment of the disease [157].”

In the citing paper

“The studies showed that a panel of cytokines, rather than a single biomarker, improve sensitivity and specificity values, with some panels showing the ability to discriminate between different stages of disease.”

In the citing paper

“Another ovarian tumor marker, CA-19-9, has been shown to be elevated in endometriosis and has a comparable or lower sensitivity than CA-125 for the detection of endometriosis [23].”

In the citing paper

“Despite extensive research, no single biomarker nor a panel of biomarkers in peripheral blood has been validated as a diagnostic test for endometriosis [17, 20].”

In the citing paper

“Overall, most endometriosis biomarker studies have remained at the level of Phase I [23] and only a few have made it to Phase II studies.”

In the citing paper

“At present, such a test does not exist [17, 20].”

In the citing paper

“Putative endometriosis biomarkers are mostly glycoproteins, growth or adhesion factors, hormones, or proteins related to immunology or angiogenesis [17, 23, 30].”

In the citing paper

“Levels of the sICAM-I have been suggested to rise during early stages of endometriosis (I-II) and decrease at stage III-IV [23].”

In the citing paper

“Its usefulness as biomarker for endometriosis is unclear, as some studies show elevated blood levels in endometriosis patients while other studies do not record a significant difference [23, 67].”

In the citing paper

“Follistatin, an inhibitor of activin, has been shown to be increased in endometriosis patients [23], especially in a subgroup of patients with ovarian endometrioma, and showed good sensitivity and specificity [43].”

In the citing paper

“The inflammatory marker C-reactive protein (CRP) has been shown to be upregulated [23], especially when examined with a high sensitivity assay making it possible to detect subclinical inflammation in women with endometriosis [50].”

In the citing paper

“However, other studies could not find an upregulation [23, 51].”

In the citing paper

“Other growth factors, such as soluble epidermal growth factor (EGF) and platelet-derived growth factor (PDGF) have been investigated, but no difference was found between endometriosis patients and control women [23].”

In the citing paper

“Both total immunoglobulin levels and antiendometrial antibodies have been investigated as potential biomarkers for endometriosis of which the latter showed the most promising results, being more commonly present in endometriosis patients than in controls [23].”

In the citing paper

“Hepatocyte growth factor (HGF) was suggested to be elevated in women with endometriosis [72], although this was not confirmed in an additional study [23, 73].”

In the citing paper

“These studies have shown promising results; however, proteomics technologies are costly and time-consuming [23], and there is a need for better standardization and reproducibility of proteomic technologies before they can be used reliably in clinical research projects [17].”

In the citing paper

“Elevations of fibroblast growth factor-2 (FGF-2), angiogenin, and soluble Flt-I (VEGFR-1) in serum of women with endometriosis have all been recorded [23].”

In the citing paper

“A range of cell populations, including T cells, B cells, natural killer (NK) cells, macrophages/monocytes, and polymorphonuclear neutrophils, has been compared between endometriosis patients and healthy controls [23]. However, for none of these populations the utility as an endometriosis biomarker has been proven [23, 96].”

In the citing paper

“No consensus exists on changes in steroid hormone levels [23].”

In the citing paper

“Contrasting evidence exists on prolactin, leptin, luteinizing hormone (LH), and adiponectin levels in endometriosis patients versus controls, showing either no difference, an increase (prolactin, leptin LH) or a decrease (adiponectin) [23, 75, 76].”

In the citing paper

“Likewise, specific antibodies against carbonic anhydrase, transferrin, α2-HS glycoprotein, lipid peroxide modified rabbit serum albumin, copper oxidized low-density lipoprotein and malondialdehyde-modified low-density lipoprotein, laminin-I, and cardiolipin have shown promise as potential endometriosis biomarkers [23].”