Purpose: Ductal carcinoma in situ (DCIS) is increasingly detected as a nonpalpable lesion on mammographic screening performed for the early detection of breast cancer. Because of the growing incidence of mammographically detected DCIS, the present study was undertaken to determine the outcome of treatment of nonpalpable, mammographically detected intraductal carcinoma of the breast using breast-conserving surgery and definitive breast irradiation.
Materials and methods: An analysis was performed of 110 women who presented with unilateral, nonpalpable, mammographically detected intraductal carcinoma of the breast and who were treated with breast-conserving surgery and definitive breast irradiation at 10 institutions in Europe and the United States. In all patients, complete gross excision of the primary tumor was performed, and breast irradiation was delivered with definitive intent. When performed, pathologic axillary lymph node staging was node negative (n=29). The median follow-up time was 9.3 years.
Results: The 10-year actuarial overall survival rate was 93%, and the 10-year actuarial cause-specific survival rate was 96%. The 10-year actuarial rate of freedom from distant metastases was 96%. There were 15 local recurrences in the treated breast. The actuarial rate of local failure was 7% at 5 years and 14% at 10 years. The histology of the local recurrence was intraductal carcinoma in 9 cases and invasive ductal carcinoma (with or without associated intraductal carcinoma) in 6 cases. The median time to local recurrence was 5.0 years (mean, 5.4; range, 2.1-15.2). With a median follow-up time of 4.4 years after salvage treatment, 14 of the 15 patients with local recurrence were alive without evidence of disease at the time of last follow-up examination. The crude incidence of local recurrence was 7% (3/42) when the final pathology margin of tumor excision was negative, 29% (5/17) when the margin was close or positive, and 14% (7/51) when the margin was unknown. There was no difference in the rate of local recurrence based on pathologic characteristics of the primary tumor.
Discussion: Results from the present study demonstrate high rates of overall survival, cause-specific survival, and freedom from distant metastases at 10 years following the treatment of nonpalpable, mammographically detected DCIS of the breast using breast-conserving surgery and definitive breast irradiation. Local recurrences within the treated breast were detected early and were treated with salvage for cure. These results support the initial treatment of nonpalpable, mammographically detected DCIS of the breast using breast-conserving surgery and definitive breast irradiation. Improvements in patient selection have the potential to reduce the risk of local recurrence.