Local control in young women with early-stage breast cancer treated with hypofractionated whole breast irradiation

Objective: To compare local control (LC) in young women with early-stage breast cancer (BC) treated with hypofractionated (HF) whole breast irradiation (WBI) vs conventional fractionation (CF) following breast-conserving surgery (BCS).

Materials and methods: Women <50 years with pT1-2N0 BC following BCS treated with WBI, CF (50Gy/25 fractions) or HF (42.4Gy/16 fractions) followed by a tumor bed boost (10-16Gy/5-8 fractions) from 2009 to 2013 were identified from an institutional database. Median follow-up was 5.2 years (range 0.3-8.4). Kaplan-Meier analysis was used to estimate 5-year LC. Logistic regression identified factors associated with receipt of CF vs HF WBI.

Results: Of 270 eligible women, 227 (84%) were treated with HF and 43 (16%) with CF WBI. A tumor bed boost of 10 Gy/5 fractions was given in 97% of patients, 53% received adjuvant chemotherapy and 94% (225/239) with estrogen-positive disease received endocrine therapy. Median age was 45 years (range 30-49) in HF and 40 years (range 19-49) in the CF group. The 5-year LC rate was 99.3% (95% CI 97.9-100%, p = 0.495) in the HF and 97.5% (95% CI 92.8-100%) in the CF group. On univariate analysis, age ≤ 40 years or triple negative BC was associated with a decreased likelihood of receiving HF WBI. Only age remained significant on multivariate analysis [OR 2.82 (95% CI 1.45-5.48, p = 0.002)].

Conclusions: HF WBI was associated with excellent LC rates in this study cohort, comparable to CF WBI. However, CF WBI was more likely to be recommended to women <40 years.