ESTRO 2024 - Abstract Book

S653

Clinical - Breast

ESTRO 2024

We retrospectively analyzed the data of our first 23 consecutive patients receiving hypofractionated RT and concurrent T-DM1. Clinical data of patients and tumor characteristics are shown in Table 1. All patients had a grade 3 ductal infiltrating carcinoma (DIC) at diagnoses and received neoadjuvant chemotherapy plus HER2 targeted therapy. After surgery, all patients received T-DM1 ( 3.6 mg/kg of body weight intravenously every 3 weeks). RT was administered according to our institutional standards: dose to chest wall, or residual breast and/or regional nodes was 42,56 Gy in 16 fractions of 2,66 Gy/die. SIB boost was administered on tumor bed to all conservative surgery patients, up to 50 Gy in 3,125 Gy fractions. Each patient received at least one cycle of TDM-1 during RT course. Skin and breast gland toxicity were evaluated in accordance with Common Terminology Criteria of Adverse Events (CTCAE) version 3.0. All patients were weekly examined during RT, and then every 6 months.

Results: