Clinical results of breast conserving therapy for stage I and II breast cancers: Assessment of local recurrences in relation to surgical margins

Background Because of previously reported shortened follow-up periods, breast conserving therapy is still not prevalent for patients with breast cancer in Japan. This is a report of clinical trial results. Methods Between November 1987 and October 1995, breast carcinomas in 462 patients were treated with breast conserving therapy (BCT). Three hundred and sixty-four patients with follow-up periods of longer than 1 year, excluding simultaneous bilateral breast carcinomas, were analyzed. There were 19 stage 0,211 stage I, 132 stage II, and 2 stage III tumors according to the 1987 UICC classification. A total dose of 50 Gy was delivered over 5 weeks to the preserved breast using⁶⁰Co γrays. The primary site was boosted with a total dose of 10 Gy in 5 fractions in 40 of the 83 patients whose tumor margins were either positive or close. Results In a follow-up period of 12 to 96 months with a median of 35 months, 8 patients developed a breast recurrence. The actuarial overall, relapse-free, and breast-recurrence-free survival at 5 years were 99.0%, 92.3%, and 97.8%, respectively. The difference in the local control rate was significant between patients with negative margins and those with positive margins (P<0.0001), and between the patients with negative margins and those with close margins (P=0.0284). Conclusions The 5-year results of our trial were similar to those of other reported series. Positive and close margins are risk factors for breast recurrence. Improvements in optimal methods of radiation therapy including boost irradiation are needed.