3562 - Hypofractionated Pelvic Radiotherapy for Symptom Control in Metastatic Rectal Cancer: A Retrospective Analysis
Presenter(s)
N. Wang1, H. Ma1, T. Xu1, H. Li1, J. Shuai2, H. Fang1, Y. Song1, B. Chen3, N. Lu1, H. Jing3, X. Liu1, S. Qi3, W. Zhang1, Y. Liu3, Y. LI1, S. Wang3, J. Jin1,4, and Y. Tang5; 1State Key Laboratory of Molecular Oncology and Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), Beijing, China, 2State Key Laboratory of Molecular Oncology and Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College (PUMC), Beijing, China, 3State Key Laboratory of Molecular Oncology and Department 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, 4National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Shenzhen, China, 5Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), Beijing, China
Purpose/Objective(s):
Pelvic symptoms are prevalent in patients with metastatic rectal cancer, significantly impacting quality of life. While palliative hypofractionated radiotherapy represents a potential therapeutic approach, robust evidence supporting its efficacy remains limited. This retrospective study aimed to evaluate the clinical outcomes of a 25 Gy/5 fractions hypofractionated regimen for symptom palliation and local control in symptomatic metastatic rectal cancer patients with pelvic masses.Materials/Methods:
We conducted a retrospective analysis of 46 consecutive patients treated at our institution between January 2014 and June 2024. All patients received 5 Gy × 5 fractions (target volume includes the primary tumor and the pelvic high-risk lymph node drainage area). Clinical assessments at 1-month post-radiotherapy included symptom relief metrics, duration of symptom control, surgical conversion rates, survival outcomes, and toxicity profiles.Results:
The cohort (median age 56.5 years, range 30-85) demonstrated the following baseline characteristics: male predominance (73.9%), ECOG 1 status (84.8%), distal rectal cancer (65.2%), stage IVA disease (78.2%), and isolated liver metastasis was common (54.3%), with primary symptoms: bleeding (84.8%), obstruction (60.9%), defecation urgency (65.2%), pain (32.6%). None of the patients received pelvic re-radiotherapy. 32.6% and the remaining patients received first-line systemic chemotherapy before and after pelvic radiotherapy, respectively. At 1-month follow-up, overall symptom response rate was 89.1% (complete response: 67.4%). Among them, complete symptom resolution by type were as follows: bleeding: 93.3%, obstruction: 90.9%, defecation urgency: 83.3% and pain: 60.0%. With median follow-up 21.93 months, 3-year OS, PFS, pelvic control rate, and surgical conversion were 64.1%, 44.3%, 94.2%, and 52.2% (median interval 91 days post-RT). As to safety profile, acute grade =3 toxicity was observed 2.2% (1/46), with perianal discomfort as predominant toxicities (grade 1-2) and 15.2% (7/46) of postoperative complications observed.Conclusion:
Hypofractionated pelvic radiotherapy demonstrates rapid and durable symptom palliation with excellent local control in metastatic rectal cancer patients. The favorable toxicity profile and clinically meaningful survival outcomes suggest this approach may serve as an effective bridge to surgical intervention in selected patients.