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

PURPOSE: 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.

PATIENTS AND METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.