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Cyclophosphamide, methotrexate and fluorouracil adjuvant combination chemotherapy for breast cancer is currently used for the duration of six monthly courses. We performed a joint analysis of two studies on the duration of adjuvant cyclophosphamide, methotrexate and fluorouracil in patients with node-positive breast cancer to investigate whether three courses of cyclophosphamide, methotrexate and fluorouracil might suffice. The International Breast Cancer Study Group Trial VI randomly assigned 735 pre- and perimenopausal patients to receive 'classical' cyclophosphamide, methotrexate and fluorouracil for three consecutive cycles, or the same chemotherapy for six consecutive cycles. The German Breast Cancer Study Group randomised 289 patients to receive either three or six cycles of i.v. cyclophosphamide, methotrexate and fluorouracil day 1, 8. Treatment effects were estimated using Cox regression analysis stratified by clinical trial without further adjustment for covariates. The 5-year disease-free survival per cents (+/-s.e.) were 54+/-2% for three cycles and 55+/-2% for six cycles (n=1024; risk ratio (risk ratio: CMFx3/CMFx6), 1.00; 95% confidence interval, 0.85 to 1.18; P=0.99). Use of three rather than six cycles was demonstrated to be adequate in both studies for patients at least 40-years-old with oestrogen-receptor-positive tumours (n=594; risk ratio, 0.86; 95% confidence interval, 0.68 to 1.08; P=0.19). In fact, results slightly favoured three cycles over six for this subgroup, and the 95% confidence interval excluded an adverse effect of more than 2% with respect to absolute 5-year survival. In contrast, three cycles appeared to be possibly inferior to six cycles for women less than 40-years-old (n=190; risk ratio, 1.25; 95% confidence interval, 0.87 to 1.80; P=0.22) and for women with oestrogen-receptor-negative tumours (n=302; risk ratio, 1.15; 95% confidence interval, 0.85 to 1.57; P=0.37). Thus, three initial cycles of adjuvant cyclophosphamide, methotrexate and fluorouracil chemotherapy were as effective as six cycles for older patients (40-years-old) with oestrogen-receptor-positive tumours, while six cycles of adjuvant cyclophosphamide, methotrexate and fluorouracil might still be required for other cohorts. Because endocrine therapy with tamoxifen and GnRH analogues is now available for younger women with oestrogen-receptor-positive tumours, the need for six cycles of cyclophosphamide, methotrexate and fluorouracil is unclear and requires further investigation. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: Randomised controlled trials (RCTs) provide optimal evidence to assess the benefits of new treatments. However, clinicians routinely rely on cross-trial comparisons to assess competing treatments when head-to-head randomised comparisons are unavailable. We investigate the validity of cross-trial comparisons using individual patient data (IPD) where patients received the same treatment protocol. We also examine the extent to which statistical adjustment for baseline characteristics can account for inter-trial differences in outcomes. Patients and methods: We used pooled IPD of 378 women with advanced breast cancer assigned to oral cyclophosphamide, intravenous methotrexate and 5-fluorouracil (CMF) in the control arms of three first-line treatment RCTs (ANZ8101, ANZ8614 and ANZ0001) conducted between 1982 and 2001. The Kaplan–Meier method was used to compare progression-free survival (PFS) and overall survival (OS) across trials. Proportional hazard models were constructed to estimate the hazard rates across trials after adjustment for baseline characteristics. Results: The distribution of baseline characteristics varied across trials. There was a statistically significant difference in survival among women treated with CMF in these trials (logrank p =0.009). The median OS were 17.7, 10.3 and 10.1months for 0001, 8101 and 8614, respectively. The hazard ratios for survival, adjusted for baseline characteristics differences, were 1.44 (8614) and 1.45 (8101) compared to 0001 (p =0.03). PFS did not differ across trials (logrank p =0.38). Conclusions: Caution should be exercised when interpreting results from historical cross-trial comparisons even if the adjustment of baseline prognostic characteristics can be performed. Cross-trial comparisons have some role in hypothesis-generating, identifying and prioritising promising treatments for further investigation; however RCTs are still essential to guide sound clinical practice. [Copyright &y& Elsevier]