Postmastectomy adjuvant chemotherapy with or without radiation therapy in women with operable breast cancer and positive axillary lymph nodes: the Southeastern Cancer Study Group experience.

Between September 1976 and June 1982, 308 patients with operable breast cancer with 1-3 involved axillary nodes were stratified according to institution, type of mastectomy, and time from surgery to protocol entry, and then randomized to receive either six or 12 months of adjuvant chemotherapy with cyclophosphamide, methotrexate, and 5-fluorouracil (CMF). With a median time of follow-up of 33 months, relapse rates among 181 reviewed and evaluable patients are 20/85 (23.5%) for pre- and 23/96 (24%) for postmenopausal patients. Results for premenopausal women, while better than historical controls at a similar time interval, appear inferior to other published adjuvant studies (e.g., NSABP and Milan). Although total relapse rates were 23/100 (23%) for six months and 20/81 (25%) for 12 months of therapy, suggestive differences were encountered by menopausal status with early trends favoring 12 months of treatment for premenopausal patients and six months of treatment for postmenopausal patients. During this same period, 283 patients with four or more involved axillary nodes were randomized to 1-3 treatment arms: six months of CMF, six months of CMF preceded by local-regional x-ray therapy (XRT), or 12 months of CMF. The latter arm was closed in February 1980 while the two six-month chemotherapy arms remain open as of January 1983. Relapse rates for 174 reviewed and evaluable patients on the three arms include: 27/76 (36%) for six months CMF, 15/54 (28%) for XRT and CMF, and 24/44 (45%) for 12 months CMF. Local-regional relapse rates were 12/120 (10%) for the combined two non-XRT arms and 3/54 (6%) for the XRT treatment arm (p = 0.34). Thus, at this early stage of follow-up there are still no statistically significant differences between six or 12 months of adjuvant CMF therapy and neither definite beneficial nor detrimental effects of prechemotherapy adjuvant radiation therapy. Longer follow-up will be needed to provide definitive conclusions.