Retrospective Analysis of Acute Toxicity Following Breast Cancer Re-Irradiation.

PURPOSE: To evaluate the acute skin toxicity and treatment-related factors in patients undergoing breast re-irradiation in a tertiary cancer centre. METHODS: A retrospective review was conducted of patients who received a repeat course of breast or chest wall radiation for ipsilateral breast cancer recurrence between April 20, 2011, and December 31, 2023. Patient characteristics, treatment parameters, and clinician-graded acute toxicity were recorded. Associations between toxicity and treatment factors were analyzed. RESULTS: Seventy patients met inclusion criteria. Acute skin toxicity was lower during retreatment than initial treatment with 22.9% of patients (n = 16) developing moderate/severe reactions during re-irradiation compared with 51.4% (n = 36) during the initial course. Severe toxicity at retreatment was not common, including moist desquamation in 10 patients (14.3%). Toxicity during the initial course did not predict toxicity during re-irradiation (P = .75). Across all fractionation schedules, no significant associations were observed between dose regimen and symptoms such as pruritus, pain, erythema, discoloration, edema, burning, dry desquamation or moist desquamation. CONCLUSIONS: Breast re-irradiation was well tolerated in the acute setting, with toxicity patterns influenced primarily by radiation dose and delivery. The findings emphasize the need for ongoing prospective work to assess long-term outcomes.