Local recurrences after different treatment strategies for ductal carcinoma in situ of the breast: a population-based study in the East Netherlands.

PURPOSE: Outcomes after different treatment strategies for ductal carcinoma in situ (DCIS) of the breast were analyzed for a geographically defined population in the East Netherlands. METHODS AND MATERIALS: A total of 798 patients with a first diagnosis of DCIS between January 1989 and December 2003 were included and their medical records were reviewed. Survival rates for ipsilateral recurrences were calculated by the Kaplan-Meier method and a multivariate Cox proportional hazards regression model was used to evaluate the prognostic significance of different variables. RESULTS: The 5-year recurrence-free survival was 75% for breast conserving surgery (BCS) alone (237 patients) compared with 91% for BCS followed by radiation therapy (RT; 153 patients) and 99% for mastectomy (408 patients, p < 0.01). Independent risk factors for local recurrences were treatment strategy, symptomatically detected DCIS, and presence of comedo necrosis. Margin status reached statistical significance only for patients treated by BCS (hazard ratio, 2.0; 95% confidence interval, 1.1-4.0) whereas significance of other prognostic variables did not change. CONCLUSIONS: In a defined population outside a trial setting, RT after BCS for DCIS lowered recurrence rates. Besides the use of RT, a microscopically complete excision of DCIS is essential. This is especially true for patients with symptomatically detected DCIS and with tumors that contain comedo necrosis, as these groups are at particular high risk for recurrent disease