Adding a Tumor Bed Boost to Whole-Breast Irradiation for Ductal Carcinoma in Situ
Posted: Friday, January 22, 2021
According to Boon Hui Chua, MBBS, of the University of New South Wales, Sydney, and colleagues, patients with ductal carcinoma in situ who received a tumor bed boost after conventional or hypofractionated whole-breast irradiation seemed to experience significantly reduced rates of local recurrence. The multicenter phase III BIG3-07/TROG 07.01 trial results were presented during the virtual 2020 San Antonio Breast Cancer Symposium (SABCS; Abstract GS2-04).
A total of 1,608 patients were assigned to receive conventional (50 Gy in 25 daily fractions) or hypofractionated (42.5 Gy in 16 daily fractions) whole-breast irradiation with or without a tumor bed boost (16 Gy in 8 daily fractions) in one of three randomization categories. Those in randomization A underwent either conventional or hypofractionated whole-breast irradiation with or without a boost. Patients in randomizations B and C received conventional and hypofractionated whole-breast irradiation, respectively, with or without a boost.
The 5-year free-from-local-recurrence rates with and without the boost were 97% versus 93%, respectively (P < .001). Invasive local recurrences occurred in 45% of patients treated with the boost and in 44% of those without. The boost's effect did not seem to be significantly impacted by age, tumor size, nuclear grade, surgical margin, or endocrine therapy.
The 5-year free-from-local-recurrence rates did not seem to differ between the conventional and hypofractionated whole-breast irradiation groups in randomization A (both 94%; P = .84) and in all randomly assigned patients (both 95%; P = .89). Additionally, the interaction between boost and dose fractionation did not appear to be significant in randomization A or in all randomly assigned patients (both P = .89). The rates of breast pain (grade ≥ 2: 12% vs. 16%; P = .84) and skin and subcutaneous tissue fibrosis (6% vs.15%; P = .14) did not seem to significantly differ between the groups.
Disclosure: For full disclosures of the study authors, visit sabcs.org.
