ESTRO 2025 - Abstract Book

S595

Clinical - Breast

ESTRO 2025

3722

Digital Poster Safety Study of Concurrent CDK4/6 Inhibitor Combined with Endocrine Therapy During Postoperative Radiotherapy for HR+/Her-2-Negative Breast Cancer Ning Han, Na Zhang deparment of radiation oncology, cancer hospital of China Medical University;Cancer hospital of Dalian University;Liaoning Cancer Hospital & Institute, Liaoning Province, China Purpose/Objective: This study aims to evaluate the safety of adjuvant radiotherapy combined with CDK4/6 inhibitor therapy following modified radical mastectomy for HR+/Her-2-negative breast cancer patients. Material/Methods: A meticulously cohort of 126 patients who underwent radiotherapy after modified radical mastectomy between January 2023 and December 2023 are selected. Among them, 35 patients received concurrent CDK4/6 inhibitor combined with endocrine therapy during radiotherapy, while 91 patients underwent radiotherapy with endocrine therapy. Paired t-test and chi-square test were used to compare dosimetric parameters, radiotherapy side effects, and hematological indices during radiotherapy between the two groups, and differences between the two sets of data were derived. Results: Compared with radiotherapy concurrent the endocrine therapy group after radical mastectomy for breast cancer, the incidence of grade≥ 2 radiation pneumonia is significantly increased in the radiotherapy concurrent CDK4/6 inhibitor combined with endocrine therapy group ， the incidence is 42.86%(n=15), while the incidence of grade≥ 2 radiation pneumonia in the radiotherapy combined with endocrine therapy group is 3.30% (n=3). The difference between the two groups was statistically significant (P<0.01). However, there was no statistically significant difference in radiation-induced esophageal injury and bone marrow suppression between the two groups. Conclusion: The incidence of grade ≥ 2 radiation pneumonitis in patients undergoing concurrent radiotherapy with CDK4/6 inhibitors and endocrine therapy is significant incresed ， but the incidence of other side effects(bone marrow suppression and radiation esophagitis) is not increased.

Keywords: CDK4/6 inhibitor, radiation pneumonia

3744

Digital Poster Feasibility of nipple-areola complex preservation in retroareolar disease: oncological outcomes and therapeutic implications Dario Cassetti 1 , Alessandra Rossi 1 , Ilaria Gaggelli 1 , Cinzia Tommasi 1 , Silvia Nesi 1 , Icro Meattini 2 , Carlotta Becherini 2 , Viola Salvestrini 2 , Marianna Valzano 2 , Luca Visani 2 , Lorenzo Livi 2 , Jacopo Nori 3 , Federica Di Naro 3 , Diego De Benedetto 3 , Lorenzo Orzalesi 1 1 Breast Surgery Department and Breast Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy. 2 Radiation Oncology and Breast Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy. 3 Breast Radiology Department and Breast Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy

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