A Systematic Overview of Chemotherapy Effects in Breast Cancer

Abstract

A systematic review of chemotherapy trials in several tumour types was performed by The Swedish Council of Technology Assessment in Health Care (SBU). The procedures for the evaluation of the scientific literature are described separately (Acta Oncol 2001; 40: 155-65). This synthesis of the literature on chemotherapy for breast cancer is based on 233 randomised studies, 9 meta-analysis of randomised studies, a population-based cohort study and 18 overviews/retrospective analyses including a total of 155,243 patients. The conclusions reached can be summarised into the following points: Adjuvant treatment-- There is solid scientific support from randomised studies that adjuvant polychemotherapy at 10 years will result in an absolute mortality reduction for patients younger than 50 years by 12% for node positive (34% relative mortality reduction corresponding to an estimated median survival prolongation of several years) and 6% for node negative patients. For women aged 50 to 69 years, the corresponding figures for node positive and node negative patients are 6% and 2%, respectively (approximately 11% relative mortality reduction). Anthracycline-containing combinations result in an absolute survival benefit at five years of 3%, compared with non-anthracycline based polychemotherapy. There are indications that the taxane paclitaxel may further improve the survival compared with anthracyclines. However, the limited data preclude conclusions for the routine care. The addition of tamoxifen to chemotherapy further enhances the survival benefit for receptor positive subgroups. The roles of more dose-intensive regimens, including high-dose therapy with stem cell support, are presently studied in randomised investigations. The data presented so far are conflicting but they do not in general support high-dose therapy. Quality of life, based on analyses of randomised studies, demonstrate that adjuvant polychemotherapy has an initial detrimental effect, but long-term follow-up of treated patients demonstrates no impairment of quality of life compared with untreated patients. Polychemotherapy in standard doses should be offered to premenopausal node positive patients, and the corresponding postmenopausal group with a receptor-negative breast cancer and to node negative patients with high risk factors. Polychemotherapy should be combined with tamoxifen to all patients with receptor-positive tumours. Due to a need of more knowledge in this field, patients should be included in investigational protocols. Locally advanced breast cancer-- Based on current knowledge, treatment of patients with locally advanced breast cancer should include neoadjuvant/preoperative polychemotherapy since there is evidence from controlled studies that such therapy will statistically significantly increase the number of patients who can be offered breast-conserving surgery. Indirect comparisons also demonstrate survival improvements, but the scientific support is equivocal. Metastatic breast cancer-- The median survival for patients with metastatic disease treated with conventional chemotherapy doses and regimens is 12 to 24 months. Retrospective cohort studies indicate that the use of non-anthracycline containing chemotherapy compared with no chemotherapy might add a survival gain of six to nine months. However, this estimation is based on equivocal data. Based on overview data, polychemotherapy results in a statistically significant survival gain compared with single-agent therapy. Based on repeated randomised studies, the addition of anthracyclines increases the response rate and statistically significantly improves the survival compared with non-anthracycline containing chemotherapy, except for CMF combined with prednisone/prednisolone, which will statistically significantly improve the survival compared with some anthracycline combinations. Second line therapy using vinorelbine or docetaxel is statistically significantly better than other regimens with a time to progression and survival benefit in the order of one to three months based on few randomised studies. The role, if any, of third line therapy is yet to be demonstrated. In the metastatic setting, conventional chemotherapy improves the quality of life. In standard care, first line therapy should contain an anthracycline and second line therapy using vinorelbine or docetaxel could be offered to selected patients failing first line therapy. Based on numerous randomised studies, breast cancer demonstrates a positive dose-response relationship both in the adjuvant situation and for metastatic disease. However, in the conventional dose-range there seems to be a plateau in the dose-response curve, with no further survival gains for high