ESTRO 2025 - Abstract Book

S573

Clinical - Breast

ESTRO 2025

(8%). Tumor bed boost was delivered in 222 patients of which 175 patients had 10 Gy/5 fx and 47 patients had 16 Gy/8 fx. Induration rates were higher in the RS group compared to the NoRS group. At 3 years, rates were 15.8% vs. 11.6%, and at 5 years, 19.9% vs. 14.9%, HR 0.79 (95% CI, 0.60-1.04) (Figure 1). For patients receiving a boost, rates at 3 years were 22.0% (RS) vs. 18.9% (NoRS), and at 5 years, 30.7% (RS) vs. 25.7% (NoRS). In patients without a boost, 3-year rates were 14.9% (RS) vs. 10.7% (NoRS), and 5-year rates were 18.4% (RS) vs. 13.5% (NoRS) (Table 1). Conclusion: Repeat surgery was associated with an increased cumulative incidence of grade 2–3 breast induration at 3 and 5 years, with further increases observed in patients receiving a tumor bed boost. Compared to using a boost, RS appears to induce less induration of the breast. Adjustments for age, smoking, and irradiated breast volume will be conducted in the final analysis presented at ESTRO 2025 [4, 5]

Keywords: Repeat surgery, breast cancer, late effect

References: 1. American Cancer Society. Understanding a Breast Cancer Diagnosis. 2021. 2. Offersen BV, et al. Partial vs. whole breast irradiation: DBCG Partial Breast Irradiation Trial. J Clin Oncol. 2022;40(36):4189-97. DOI: 10.1200/jco.22.00451. 3. Offersen BV, et al. Hypofractionated vs. standard radiotherapy: DBCG HYPO Trial. J Clin Oncol. 2020;38(31):3615 25. DOI: 10.1200/jco.20.01363.