Long-term results of breast conserving surgery for stages I and II breast cancer: experiences at Osaka Medical Center for Cancer and Cardiovascular Diseases.

Abstract

The purpose of this study is to summarize the long-term results of breast conserving surgery (BCS) for Japanese patients with stage I and II breast cancer at a single institute and to identify risk factors for local recurrence after BCS. Between October 1986 and June 2000, 979 women underwent BCS with or without radiation therapy (RT). Overall survival, disease free survival and local recurrence rates were calculated by the Kaplan-Meier method. Risk factors for local recurrence were examined by multivariate analysis using the Cox proportional regression model. The 10-year overall survival rates were 90.9% for the surgery and radiation therapy (RT group) and 89.3% for the surgery only group with a median follow-up time of 46 months. The 10-year disease free survival rates were 85.1% in the RT group and 69.2% in the surgery only group (p=0.0001). The positive margin rate was 14.1% (138/979). The 10-year overall survival rate of the patients with positive margins was 87.9%, compared with 90.8% for patients with negative margins (N.S.). The cumulative incidence of local recurrence at 10 years was significantly lower in the RT group (7.2% ) than in the surgery only group (27.5% ) (p<0.0001). Multivariate analysis showed that positive margins and lack of post-operative irradiation or adjuvant endocrine therapy were risk factors for non-inflammatory local recurrence. Our study indicates that BCS can be performed for Japanese women with early breast cancer. The margin status and post-operative irradiation had no influence on overall survival while but were significantly related to local recurrence.