ESTRO 2025 - Abstract Book

S473

Clinical - Breast

ESTRO 2025

Results: With a median follow-up of 37 months (range 12-52), all patients remain alive with no locoregional or distant recurrence. Acute toxicity was mild, with grade 1 skin toxicity in 58% and grade 2 skin toxicity in 5%, and grade 1 breast edema in 10% and grade 2 in 1%. No grade 3 or higher acute toxicities were observed. At a minimum follow-up of 12 months, early-late toxicity included grade 1 breast edema in 3%, grade 1 hyperpigmentation in 9%, and grade 1 fibrosis at the tumor bed in 6%. Additionally, 21% of patients reported grade 1 and 2% grade 2 local pain throughout treatment and follow-up. A Pearson's chi-square test indicated a significantly lower risk of any acute toxicity for that patients with breast PTV below median value of 724 cc (41.8% vs 58.2%, p = 0.030) and boost PTV below median value of 25 cc (43.3% vs. 56.7%, p = 0.042) as well as a lower risk for any late complications in women with breast PTV ≥724 cc (23.1% vs. 76.9%, p = 0.041) (Figure 1).