ESTRO 2024 - Abstract Book

S632

Clinical - Breast

ESTRO 2024

90. Pesch B, Kendzia B, Gustavsson P, Jöckel KH, Johnen G, Pohlabeln H, et al. Cigarette smoking and lung cancer- -relative risk estimates for the major histological types from a pooled analysis of case-control studies. Int J Cancer. 2012;131(5):1210-9. 91. Castellsagué X, Muñoz N, De Stefani E, Victora CG, Castelletto R, Rolón PA, et al. Independent and joint effects of tobacco smoking and alcohol drinking on the risk of esophageal cancer in men and women. Int J Cancer. 1999;82(5):657-64.

92. Polednak AP. Estimating the number of U.S. incident cancers attributable to obesity and the impact on temporal trends in incidence rates for obesity-related cancers. Cancer Detect Prev. 2008;32(3):190-9.

2226

Digital Poster

Clinical and dosimetric aspects in concurrent radiotherapy with CDK4/6 inhibitors in breast cancer.

Laura Florentina Rebegea 1,2,3 , Ana Maria Ilie 1 , Rodica Anghel 4 , Mihaela Lungu 5,2 , Mihaela Emilia Dumitru 1

1 “Sfantul Apostol Andrei” Emergency Clinical Hospital, 800578, Departmen of Radiotherapy, Galati, Romania. 2 Faculty of Medicine and Pharmacy, “Dunarea de Jos” University, Medical Clinical Department, Galati, Romania. 3 “Dunarea de Jos” University, Research Center in the Field of Medical and Pharmaceutical Sciences, ReFORM -UDJ, Galati, Romania. 4 ”Carol Davila” University of Medicine and Pharmacy, Medical Clinical Department, Bucharest, Romania. 5 “Sfantul Apostol Andrei” Emergency Clinical Hospital, 800578, Departmen of Neurology, Galati, Romania

Purpose/Objective:

CDK4/6 inhibitors (CDK4/6i) and endocrine therapy are used to treat ER (+), HER2-negative metastatic or locally advanced breast cancer. Radiotherapy (RTE) is often needed for adjuvant and metastatic breast cancer patients, but few studies are known about the safety of CDK4/6i with radiotherapy. CDK4/6i synergistically radio-sensitizes in most preclinical studies.

Material/Methods:

This study includes 48 metastatic or locally advanced breast cancer patients (93.75% women and 6.25% men) treated with radiotherapy concurrent with Palbociclib (72.92%), Abemaciclib (18.75%) or Ribociclib (8.33%) between December 2019 and June 2023. Median age was 63 (range 34-85 years). The median follow-up period was 28 months (range 3-42 months).

Results:

Forty-four patients (91.67%) received palliative radiotherapy, adjuvant therapy performed 4 patients (8.33%), including 60 metastatic sites. Bone metastasis was most common treated sites (68.75% of cases), followed by