Radiation treatment for ductal carcinoma in situ (DCIS): is a boost to the tumor bed necessary?

The aim of the presented study was to evaluate the long-term outcome of breast-conserving surgery and radiation for the treatment of ductal carcinoma in situ (DCIS) and the role of the radiation boost to the tumor bed. The files of 75 women with DCIS treated by breast-conserving surgery followed by definitive radiation from 1988 to 1997 were reviewed for demographic data, prognostic variables, radiation dose, radiation boost, recurrence, and outcome. Total radiation dose was 5000 cGy delivered in 25 fractions. Twenty patients (26.7%) received an additional boost to the tumor bed of 1000 cGy in 5 fractions. Median follow-up time was 81.5 months (range, 22-145). Pearson correlation coefficient and its significance was calculated between the variables. Log rank test was used to analyze differences in local recurrence rates between patients who did or did not receive a boost, and a Cox regression model was fitted to the data to predict recurrence. Ten patients (13%) had local recurrence; one patient showed lymphatic spread. Histopathologic examination revealed DCIS in 6 cases (60%) and invasive duct carcinoma in 4 (40%)(one minimally invasive). The recurrence group included 3 of the 20 patients who received a radiation boost (15%) and 7 of the 55 who did not (12.7%) (p=0.7). Correlation analysis of patient characteristics, prognostic factors, and treatment was significant only between mastitis as the presenting symptom (n=4) and longer time to recurrence (p=0.02). The recurrence rate in the present study was similar to other series of conservative treatment for DCIS of the breast. No additional value was found for the radiation boost. Larger controlled randomized studies are needed to confirm these findings.