ESTRO 2024 - Abstract Book

S654

Clinical - Breast

ESTRO 2024

From June 2020 to October 2023 twenty-tree patients completed the prescribed RT course. The most used chemotherapy regimen was “epirubicin and cyclophosphamide and weekly paclitaxel and Trastuzumab” (10/23 patients), followed by “dose - dense epirubicin/cyclophosphamide followed by paclitaxel + Trastuzumab” in 9/23 patients. Radiotherapy volumes, technical details, dosimetric parameters and toxicity outcomes are reported in Table 2. All patients tolerated RT well and none discontinued treatment. The most common side effect was mild radiodermitis: 7/23 patients presented grade 1, while 4/24 patients showed grade 2 reactions. No grade ≥ G3 acute toxicity was reported. One- year late toxicity was evaluated for 10/23 patients, with five skin/breast toxicity ≥ G3. No acute nor late ≥ G1 toxicity in the “regional node field” was reported.

Conclusion:

Hypofractionated radiotherapy concomitant to TDM1 showed a substantially low acute toxicity profile, both for primary and regional node regions. Patients who developed early higher toxicity showed further worsening over time. This finding seems to suggest the need for evaluation of risk factors (BMI, PTV cc) for local complications when considering a hypofractionated regimen.

A larger number of patients and further follow up, appropriately integrated with cardiological evaluations, will clarify the impact on cardiac toxicity of hypofractionated RT in association with TDM1.

Keywords: Hypofractionation, TDM1, Node irradiation breast