ESTRO 2024 - Abstract Book

S666

Clinical - Breast

ESTRO 2024

Anna Giulia Becchetti 1 , Laura Di Lena 1 , Elisabetta Perrucci 2 , Lorenzo Falcinelli 2 , Simonetta Saldi 2 , Vittorio Bini 3 , Isabella Palumbo 1,2 , Cynthia Aristei 1,2 1 University of Perugia, Radiation Oncology Section, Perugia, Italy. 2 Perugia General Hospital, Radiation Oncology Section, Perugia, Italy. 3 University of Perugia, Internal Medicine, Endocrinal and Metabolic Science, Perugia, Italy

Purpose/Objective:

Aim of the present study is to update data reported in a previous study (1) that evaluated skin and subcutaneous toxicity in early breast cancer (BC) patients treated with post-operative hypofractionated whole breast irradiation (WBI) with or without a sequential hypofractionated boost (HB).

Material/Methods:

From January 2014 to August 2015, 219 patients, median age 62 years (range 34-88), were enrolled. Patients were treated with breast conserving surgery (BCS) and post-operative hypofractionated WBI in 16 fractions to a total dose of 42.4 Gy. Patients with negative prognostic factors received a HB of 2.65 Gy for 4 or 5 (when margins were focally positive) fractions. All treatments were administrated using a three-dimensional conformal radiotherapy (3DCRT) technique. Systemic adjuvant treatments were hormonal therapy (HT) and/or chemotherapy (CHT) and/or Trastuzumab. Toxicities were assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Univariate and multivariate analyses estimated predictive factors for skin and subcutaneous late toxicity. Toxicity was related to patient factors (hypertension, diabetes and collagenopathies) and to treatment factors (number of excised lymph nodes, CHT, HT and HB administration). Trastuzumab was not considered since it was prescribed in only 3 patients. All calculations were performed using the Statistical Package for the Social Sciences (IBM-SPSS version 16) program. One hundred and sixty-five/219 patients resulted evaluable for the present study. Indeed, 17/219 patients died (7.8%; only 4 deaths were related to BC), 9/219 patients received mastectomy (4.1%; 6 of them for disease recurrence) and 28/219 patients were lost to follow up. Patients and tumor characteristics are reported in Table 1. HB was prescribed in 78/165 patients (47.3%), in 24 (14.5%) patients ≥ 10 lymph nodes were removed, 133 (80.6%) patients received HT and 30 (18.2%) CHT. Median follow up was 8.6 years (range 6.7-9.6). Late toxicity was recorded in 15.8% (26/165), hyperpigmentation G1 in 3.6% (6/165), induration/fibrosis G1 in 13.3% (22/165) and telangiectasia G1 in 1.8% (3/165). No other toxicities were reported and no late G2-3 toxicities occurred. In our previous study (1), at 12 months after the end of treatment, late toxicity was recorded 46/219 (21%) patients. At the present analysis late toxicity was reduced to 15.8%, with only G1 toxicities registered. In the univariate analysis number of excised lymph nodes ≥10 (p=0.003) and HB administration (p=0.041) resulted a risk factor for late toxicity. In the multivariate analysis only the number of excised lymph nodes ≥10 emerged as a risk factor for late toxicity (OR 3.431; CI95% 1.209-9.737). Results: