Platinum containing regimens for metastatic breast cancer.

Abstract

Studies have reported high tumour response rates for platinum-containing regimens in the treatment of women with metastatic breast cancer. To identify and review the evidence from randomised trials comparing platinum-containing chemotherapy regimens with regimens not containing platinum in the management of women with metastatic breast cancer. The specialised register maintained by the editorial base of the Cochrane Breast Cancer Group was searched on 2nd May 2003 using the codes for "advanced breast cancer", "chemotherapy". Details of the search strategy applied to create the register, and the procedure used to code references, are described in the Cochrane Breast Cancer Group module on The Cochrane Library. Randomised trials comparing platinum-containing chemotherapy regimens with regimens not containing platinum in women with metastatic breast cancer. Studies were assessed for eligibility and quality, and data (from published trials) were extracted by two independent reviewers. Hazard ratios were derived for time-to-event outcomes, where possible, and a fixed effect model was used for meta-analysis. Response rates were analysed as dichotomous variables. Toxicity and quality of life data (not available) were extracted where present. Thirteen eligible trials were identified, of which 12 had published time-to-event data. The quality of randomisation was generally not described.Data, based on an estimated 987 deaths in 1377 women, was unable to show a statistically significant difference in favour of platinum-containing regimens. The hazard ratio (HR) for overall survival was 1.00 (95% confidence interval (CI) 0.88 to 1.15, p=0.96), with minor heterogeneity. Results were similar when the analysis was limited to trials in women receiving first line chemotherapy. There was no statistically significant difference in favour of platinum-containing regimens for time to progression (overall HR of 1.06 (95% CI 0.95 to 1.19, p=0.31) although there was marked evidence of heterogeneity (p< 0.0001). There was a statistically significant difference in overall response in favour of platinum-containing regimens (OR 1.47; 95% CI 1.23 to 1.76, p=0.0001). However, there was strong statistical evidence of heterogeneity (p < 0.00010) probably reflecting the varying efficacy of the comparator regimens used in the trials. Heterogeneity may also reflect the differences, and difficulties, in assessing response. Women receiving platinum-containing regimens experienced statistically significant greater toxicity levels for leukopenia, hair loss, nausea and vomiting and anaemia compared with those receiving non-platinum regimens. In view of the significant excess toxicity, lack of progression or survival benefit and the availability of less toxic active agents it is difficult to justify the use of platinum-containing regimens, particularly as first line treatment for women with metastatic breast cancer in routine clinical practice. Ongoing trials are examining the possibility of synergy between platins and trastuzamab, a monoclonal antibody treatment. No randomised trials containing oxalplatin were identified for the present review.