Main Session
Sep 27
QP 01 - Multidimensional Toxicity in Breast Cancer Radiotherapy: Integrating Clinical, Patient-Reported, and Biological Outcomes

1000 - Safety of Postoperative Concurrent Capecitabine and Intensity-Modulated Radiotherapy in Triple-Negative Breast Cancer: Results from a Phase II Prospective Study

03:05pm - 03:10pm ET
Room 253

Presenter(s)

Jiaxuan Li, MD Headshot
Jiaxuan Li, MD - Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, Beijing

J. Li1, Y. Zhai1, B. Lan2, Y. Wang3, L. Zhou4, Y. Song1, X. Zhao1, S. Chen1, G. Sun1, H. Fang1, B. Chen1, Z. Yang1, N. Lu1, S. Qi1, H. Jing1, Y. Tang1, W. Zhang1, Y. X. Li1, F. Ma2, and S. L. 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 Breast Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 4Department 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):

Capecitabine is an effective adjuvant treatment for triple-negative breast cancer (TNBC), and radiotherapy is a standard component of care for most breast cancer patients. Although preclinical studies suggest a synergistic effect and concurrent use has shown promise in gastrointestinal malignancies, prospective evidence on the safety of this combination in breast cancer is limited. This phase II trial evaluates the safety of postoperative radiotherapy administered concurrently with capecitabine in TNBC patients.

Materials/Methods:

This prospective study (NCT06197581) enrolled women aged 18–70 years with TNBC requiring both adjuvant capecitabine and radiotherapy. Eligibility included mastectomy for stage T3–T4 or N+ disease, or breast-conserving surgery (BCS). Radiotherapy utilized VMAT or IMRT, with targets based on surgery type. Conventional and hypo-fractionated radiotherapy were permitted. The capecitabine regimen was determined collaboratively by medical and radiation oncologists based on prior treatment (neoadjuvant chemotherapy or not) and body surface area. Primary endpoint was grade =3 adverse events (CTCAE v5.0) during concurrent treatment and within three months post-radiotherapy. Secondary endpoints included treatment interruptions.

Results:

Between January 2024 and June 2025, a total of 40 patients with TNBC were enrolled and analyzed after screening 56 patients. The median age was 46 years (range, 27–64 years), and 50.0% were premenopausal. The predominant histology was invasive ductal carcinoma of no special type (85.0%). The distribution of clinical stage at diagnosis was as follows: stage I in 12 patients (30.0%), stage II in 17 (42.5%), and stage III in 11 (27.5%). The radiotherapy target volumes included: chest wall plus regional nodal irradiation in 11 patients (27.5%); whole breast plus tumor bed boost in 20 patients (50.0%); whole breast plus tumor bed boost plus regional nodal irradiation in 9 patients (22.5%).During radiotherapy, concurrent capecitabine was administered at the following doses: 1.0 g twice daily in 30 patients (75.0%), 1.5 g twice daily in 3 patients (7.5%), 0.5 g three times daily in 6 patients (15.0%), and 1.0 g in the morning combined with 1.5 g in the evening in 1 patient (2.5%). All patients completed radiotherapy without interruption; three required capecitabine dose modification. No grade 4 or 5 adverse events were observed during the concurrent treatment period. Most common adverse events were leukopenia (62.5%) and radiation dermatitis (60.0%). Grade 3 toxicities occurred in five patients (12.5%): dermatitis (n=3), hand-foot syndrome (n=1), and leukopenia (n=1). All patients completed planned capecitabine consolidation. All patients completed the planned course of capecitabine consolidation therapy (at least six months).

Conclusion:

Concurrent radiotherapy and capecitabine in adjuvant TNBC treatment showed safety profile with no increased toxicity, supporting future efficacy studies.