Long-term outcome after breast-conservation treatment with radiation for mammographically detected ductal carcinoma in situ of the breast

BACKGROUND. Ductal carcinoma in situ (DCIS) is detected most commonly on routine screening mammography in the asymptomatic patient, and has a long natural history. The objective of the current study was to determine the long-term outcome after breast-conservation surgery followed by definitive breast irradiation for women with mammographically detected DCIS of the breast. METHODS. In total, 1003 women with unilateral, mammographically detected DCIS of the breast underwent breast-conserving surgery followed by definitive breast irradiation. These women were treated in 10 institutions in North America and Europe. The median follow-up was 8.5 years (mean, 9.0 years; range, 0.2-24.6 years). RESULTS. The 15-year overall survival rate was 89%, and the 15-year cause-specific survival rate was 98%. The 15-year rate of freedom from distant metastases was 97%. In total, there were 100 local failures (10%) in the treated breast. The 15-year rate of an, local failure was 19%, and the 15-year rate of local only first failure was 16%. Patient age greater than or equal to 50 years at the time of treatment and negative final pathology margins from the primary tumor excision both were associated independently with a lower risk of local failure in univariate analysis (P = 0.00062 and P = 0.024, respectively) and in multivariate analysis (P = 0.00057 and P = 0.0026, respectively). For favorable subgroups of patients age greater than or equal to 50 years or with negative resection margins, the 10-year risk of local failure was less than or equal to 8%. CONCLUSIONS. The current results support the use of breast-conserving surgery followed by definitive breast irradiation for the treatment of patients with mammographically detected DCIS of the breast. Patient age greater than or equal to 50 years at the nine of treatment and negative resection margins both were associated independently with a decreased risk of local failure.