2757 - Safety of Concurrent Capecitabine and Radiotherapy in Breast Cancer Patients:A Real-World Analysis

C. Zhu¹, Y. Zhai¹, B. Lan², L. Xuan¹, L. Zhou³, Y. Liu¹, B. Chen¹, H. Fang¹, Y. Song¹, N. Lu¹, S. Qi¹, H. Jing¹, Y. Tang¹, W. Zhang¹, Y. LI¹, F. Ma², and S. Wang¹; ¹Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, ²Department of Medical Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, ³Department of Radiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China

Purpose/Objective(s): Both capecitabine and radiotherapy have been widely used for patients with breast cancer. Although concurrent capecitabine and radiotherapy showed favorable efficacy and tolerable toxicities in patients with gastrointestinal carcinoma, there is still a paucity of real-world evidence on the safety of the concurrent treatment in breast cancer. The aim of this study is to investigate the toxicity of concurrent radiotherapy with capecitabine in breast cancer patients. Materials/

Methods: Patients pathologically diagnosed as breast cancer, aged 18-70 years old, received concurrent radiotherapy and capecitabine between January 2017 and December 2020, radiation target volume involved chest wall or whole breast with and without lymph node regions, with complete medical record were selected and analyzed. Patients’ characteristics, tumor information, treatment details including irradiation dosimetric index, systemic regimens doses were assembled. Both acute and chronic adverse events (AEs) were evaluated by a senior radiation oncologist, a senior medical oncologist and a radiologist, according to National Cancer Institute common terminology criteria for adverse events, version 5.0.
Results: Totally, fifty-three patients were analyzed. Baseline characteristics are shown in Table I. Four of them received concurrent chemoradiotherapy after local recurrence. Hypofractionation radiation, with total dose of 43.5Gy-49.5Gy, 2.9Gy per fraction, were delivered to 36 patients and the remaining patients received conventional fractionation radiotherapy, with dose of 50-62.5 Gy, 1.8-2Gy per fraction. Thirty-nine patients (73.6%) were treated with concurrent capecitabine at a dose of 1000mg/m2 bid d1-14/q3w, and the remaining 14 patients (26.4%) were treated with a low-dose maintenance therapy at 500mg tid. The median follow-up time was 26.5 months. The most common side effects were dermatitis (N=45) and leukopenia (N=33) at any grade. Followed by radiation esophagitis(N=17), fatigue (N=16)and hand-foot syndrome(N=15). The most common G3 side effects were radiation induced dermatitis (N=11) and hand-foot syndrome (N=4). All of them were cured after intervention. All of the patients finished the whole course of radiotherapy. None but 1 patient discontinued concurrent medication because of gastrointestinal reaction. No grade 4-5 AE was observed.
Conclusion: In general, concurrent radiotherapy and capecitabine in breast cancer were safe with acceptable and controllable toxicities. Dermatitis should be paid more attention in clinical works.

Abstract 2757 – Table 1: Baseline Characteristics (N=1,414). **Includes mesothelioma and thymus cancers.

Variable	PRO Completion Rate (%)	Odds Ratio (95% CI)	P-Value
Race White (Ref) Black Asian Other	41.61% 28.95% 34.65% 43.28%	1 0.63 (0.41-0.97) 0.99 (0.62-1.6) 1.22 (0.71-2.11)	- 0.04* 0.99 0.47
Preferred Language English (Ref) Non-English	41.24% 20.55%	1 0.34 (0.18-0.65)	- <0.001*
Primary Cancer Site Lung/Tracheal (Ref) Esophagus Other Thoracic**	37.59% 52.58% 46.94%	1 1.64 (1.19-2.26) 1.36 (0.75-2.46)	- <0.01* 0.32
Visit Type In-Person (Ref) Virtual	41.05% 26.19%	1 0.54 (0.33-0.90)	- 0.02*