Randomized trial on the effect of radiotherapy in addition to 6 cycles CMF in node-positive breast-cancer patients

Abstract

In 1984 the GBSG started a multicenter randomized trial to compare the effectiveness of 6 cycles of cyclophosphamide, methotrexate and fluorouracil (CMF) with or without radiotherapy (RT) as adjuvant treatment in node-positive breast-cancer patients treated by mastectomy. During 5 years, 199 patients were randomized. After a median follow-up of about 9 years, the treatment groups 6 x CMF and 6 x CMF + RT were compared regarding time to recurrence and death. As the first event of failure, we observed locoregional recurrence in 22 patients, distant metastases in 66 patients, a secondary malignancy in 9 patients and death without previous event in 5 patients. For event-free survival (EFS), no significant difference was observed [relative risk (RR) 6 x CMF + RT vs. 6 x CMF 0.82, 95% confidence interval (CI) 0.55-1.21]. Event-specific analysis showed a significant decreased risk after radiotherapy for locoregional recurrence. The risk for distant metastases was estimated as slightly decreased and the risk for secondary malignancy and for death without previous event was estimated as increased in treatment group 6 x CMF + RT in comparison with treatment group 6 x CMF, but these effects were not significant. For overall survival (OS) and breast-cancer-specific survival (BCS), no significant treatment effect could be demonstrated. There is a beneficial effect of radiotherapy on locoregional recurrence. For EFS and BCS, a tendency in favour of radiotherapy is observed, but this is not significant; for OS, no difference can be demonstrated, but the power of the study is too low to detect small treatment effects.