Long-Term Clinical and Cosmetic Outcomes After Breast Conservation Treatment for Women With Early-Stage Breast Carcinoma According to the Type of Breast Boost

Purpose: The present study was performed to compare outcomes after breast conservation treatment with iridium-192 implant boost vs. electron boost. Methods and Materials: From 1977 to 1983, 141 patients were treated with whole breast radiotherapy followed by iridium-192 boost after breast-conserving surgery. They were matched 1:1 to patients treated with electron boost. Outcome measures included survival, local recurrence, cosmesis, and complications. Results: Median follow-up was 16.7 and 12.6 years for the implant vs. electron groups (p < 0.001). Rates of local recurrence, freedom from distant metastases, and overall survival at 10/20 years did not differ between the groups, nor did patterns of first failure. Patients in the electron group were more likely to have excellent/good cosmesis than those in the implant group 1 year after radiotherapy (p = 0.014); this trend continued through 10 years but did not reach statistical significance at years 5/10. Complication rates were similar, although patients receiving electron boost seemed less likely to develop breast fibrosis than did those receiving implant boost (23/141 vs. 58/141, respectively, incidence rate ratio 0.7, p = 0.17). Conclusions: Twenty-year data demonstrate no difference in rates of local recurrence, freedom from distant metastases, overall survival, or patterns of failure between groups treated with these two well-described radiotherapy boost techniques. Better cosmesis was observed in the electron group 1 year after radiotherapy, with a trend continuing for 10 years. The incidence of complications was similar between the groups, with a trend toward increased fibrosis in patients receiving implant boost.