10-Year Outcomes of Concomitant Boost Irradiation Following Breast-conserving Surgery versus Sequential Boost for Early-stage Breast Cancer treatment

Abstract

Abstract Background: Concomitant boost irradiation (CB) in adjuvant whole breast radiotherapy (WBI) is increasingly prevalent. Multiple studies have reported the effect of CB; however, long-term outcomes after CB remain unknown. Methods: Totally 266 patients administered breast-conserving surgery from March 2007 to November 2012 were included in this retrospective analysis. They were administered WBI at 45 Gy (range, 43.2-46) in 23 fractions (range, 18-25). CB irradiation was delivered shortly after WBI completion with 9 or 12 Mevβ electrons at a dose of 13.8 Gy (range, 7.2-15) in 23 fractions (range, 18-25). Sequential boost irradiation (SB) was conducted sequentially after the entire WBI treatment at a dose of 14 Gy (range, 10-15) in 7 fractions (range, 4-8). Then, 10-year survival, local control, and toxicity in these two groups were analyzed. Results: Median follow-up time was 124 months, ranging from 121.6 to 126.4. The 10-year disease-free (DFS) and overall (OS) survival rates were similar in both groups, both before and after PSM. Both distant metastasis and recurrence rates in the CB group were similar to those of the SB group after PSM. Moreover, both groups had similar cosmetic outcomes and radiation-associated late toxicity. Conclusions: Survival, local tumor control, cosmetic outcome, and late toxicity were comparable in the CB and SB groups. WBI with CB can be considered an effective therapeutic tool in early-stage breast cancer.