BACKGROUND AND PURPOSE: The influence of surgical adjuvant radiotherapy on overall survival of patients with operable breast cancer is still a controversial subject. The negative result of the EBCTCG meta-analysis (Early breast cancer trialists', collaborative group. Effects of radiotherapy and surgery in early breast cancer. An overview of the randomised trials. N. Engl. J. Med. 1995;333:1444-1455) of clinical randomized trials on adjuvant radiotherapy in breast cancer is in strong contrast with the Danish 82B, 82C and British Columbia trials (Overgaard M, Hanse PS, Overgaar J, et al. Postoperative radiotherapy in high-risk premenopausal women with breast cancer who receive adjuvant chemotherapy. Danish Breast Cancer Cooperative Group 82b Trial. N. Engl. J. Med. 1997;337:949-955; Overgaard M, Jensen MB, Overgaard J, et al. Postoperative radiotherapy in high-risk postmenopausal breast-cancer patients given adjuvant tamoxifen: Danish Breast Cancer Cooperative Group DBCG 82c randomized trial. Lancet 1999;353:1641-1648; Ragaz J, Jackson S, Le N, et al. Adjuvant radiotherapy and chemotherapy in node-positive premenopausal women with breast cancer. N. Engl. J. Med. 1997;337:956-962) showing an impressive survival benefit. This paper tries to fill in the gap between the conflicting results. MATERIALS AND METHODS: The 36 trials of the EBCTCG (Early breast cancer trialists', collaborative group, 1995) were prospectively screened for a number of objective parameters that are usually not analyzed in review papers. The odds of death data (and its variance) were borrowed from the original meta-analysis (Early breast cancer trialists', collaborative group, 1995) to check whether the objective features were significant predictors for overall survival benefit. RESULTS: A significant survival benefit for the radiotherapy arm was found for recent trials (2P