ESTRO 2022 - Abstract Book

S1028

Abstract book

ESTRO 2022

48.0) of whom 0.6 cm 3 (0.0-5.2) in the first centimetre below the skin surface. Lung and heart dose constraints were never exceeded. Only 4 patients, out of 34, showed a grade 1 (G1) erythema and no instance of grade 2 (G2) skin toxicity was documented.

Conclusion Our findings confirmed the safety of the FAST regimen also in BC patients with fair skin and large breast volume. The use of FIF technique helped in mitigating the acute skin reactions, minimizing the target dose inhomogeneity and hot spots usually associated to a higher risk of acute adverse events and suboptimal final cosmetic outcomes. A longer follow-up and a larger patients’ population are required to confirm these results

PO-1213 Moderately hypofractionated irradiation for breast cancer: A Brazilian institution experience

G. Siqueira 1 , G. Marta 2 , S. Hanna 2 , L. Moura 1 , F. Miranda 2 , H. Carvalho 2

1 Sirio-Libanês Hospital , Departament of Radiation Oncology, Brasilia, Brazil; 2 Sirio-Libanês Hospital, Departament of Radiation Oncology, Sao Paulo, Brazil Purpose or Objective Moderately hypofractionated irradiation has been assessed in numerous clinical trials, resulting in comprehensive acceptance of shorter treatment approach for postoperative irradiation in patients with breast cancer. However, there is a lack of data on the use of moderately hypofractionated irradiation in the Brazilian population. The aim of this study was to evaluate the use of moderately hypofractionated radiation therapy for the treatment of non-metastatic breast cancer (BC) in one Brazilian Institution. Materials and Methods Data from all consecutive non-metastatic BC treated with schedules of 40Gy in 15 fractions or 42.4Gy in 16 fractions between 2010 to 2019 were retrospectively analyzed. The rates of local recurrence free survival (LRFS), regional recurrence free survival (RRFS), distance recurrence free survival (DRFS) and overall survival (OS) were estimated. Acute and late toxicity profile based on CTCAE 5.0 graduation were accessed for the entire cohort. Results A total of 676 patients were included. Median age was 57 years-old and median follow-up time was 31 months. Most of patients had stage I and II, and 81.5% underwent breast conserving surgery. Among 123 women who received mastectomy, 29% had immediate reconstruction with implants and 28% with autologous tissue. Seventy-one percent of patient presented luminal subtype tumor and 84.5% received adjuvant hormone therapy. Chemotherapy was administered in almost half of patients and all the 80 patients with Her-2 positive diseases received Trastuzumab based systemic therapy. One third of patients received regional node irradiation (RNI); boost was performed in 41.3% of treatments. The 5-year LRFS, RRFS, DRFS and OS was 95.7%, 99.6% ,91.8% and 95.9%, respectively. Acute and late side effects profile were mild and only 3.6% of patients developed grade 3 dermatitis. Conclusion In this Brazilian institution experience, moderately hypofractionated irradiation to breast, chest wall (with/without breast reconstruction), and regional lymph nodes was safe and effective with acceptable toxicity profile. Keywords: radiation therapy, hypofractionation, breast

PO-1214 Caloric restriction or intermittent fasting in cancer patients receiving curative radiotherapy

C. Vega 1 , T. Merino 1

1 Pontificia Universidad Católica de Chile, Hemato-Oncología, Santiago, Chile

Purpose or Objective