Abstract PO4-22-04: Evaluation of acute toxicity in breast cancer patients receiving concurrent capecitabine and radiation

Abstract Purpose: Adjuvant capecitabine has been shown to improve disease-free survival and overall survival in breast cancer patients who have residual disease after neoadjuvant chemotherapy, particularly in those with triple negative breast cancer (TNBC). While adjuvant chemotherapy is often completed prior to adjuvant radiotherapy (RT), capecitabine may be administered concurrent with RT to reduce the time from surgery to RT. The purpose of this study was to evaluate the feasibility of concurrent therapy and the associated rates of acute loco-regional toxicity. Materials and Methods: A retrospective chart review was performed to identify all breast cancer patients who received adjuvant capecitabine and RT. Patients with a history of prior RT, patients who were treated with capecitabine and RT sequentially, and patients who were treated with palliative intent were excluded. Capecitabine was given Monday-Friday during RT. Patient and disease characteristics, capecitabine and RT treatment details, acute toxicity, and treatment breaks were recorded. Toxicity was scored by the Common Terminology Criteria for Adverse Events (CTCAE) version 5. Results: A total of 27 patients with non-metastatic breast cancer who received concurrent capecitabine and RT with definitive intent treated from 2013 to 2023 were identified. Median age at diagnosis was 52 years Interquartile Range (IQR) 40-60. Adjuvant capecitabine dose ranged from 500-1500 mg twice daily. Adjuvant RT dose ranged from 42.56 Gray (Gy) to 50.4Gy. The majority of patients (92.6%) received a sequential 10-14 Gy boost to the lumpectomy site or mastectomy scar, and 70.3% of patients received elective regional nodal RT. During treatment, all patients developed Grade 1 or 2 radiation dermatitis, while Grade 3 radiation dermatitis was noted in 4 (14.8%) patients. Two patients required a treatment break from RT, and both patients were able to subsequently complete their planned RT course. Seven patients (25.9%) required a capecitabine dose reduction or capecitabine treatment break during RT. No Grade 4 or 5 toxicities were reported. Median follow-up from RT completion was 7 months IQR 0.98-12.2. At last follow-up, radiation dermatitis had improved to Grade 0-1 for all patients. Conclusion: Concurrent adjuvant capecitabine and RT is a feasible treatment approach that is well tolerated with acceptable acute toxicities. Citation Format: Ahmed Shalaby, Zohaib Sherwani, Lara Hathout, Imraan Jan, Bruce Haffty, Mridula George, Shicha Kumar, Coral Omene, Deborah Toppmeyer, Nisha Ohri. Evaluation of acute toxicity in breast cancer patients receiving concurrent capecitabine and radiation abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-22-04.