Affiliation:
1. National Cancer Center, Chinese Academy of Medical Sciences and Peking Union Medical College
2. Sichuan University
3. Sun Yat-sen University Cancer Center
4. Chinese Academy of Medical Sciences and Peking Union Medical College
Abstract
Abstract
Purpose
The safety of an MRI simulation-guided boost after short-course preoperative radiotherapy (SCPRT) for unresectable rectal cancer is assessed with a planned interim analysis.
Methods and materials
Patients diagnosed with clinical stage T3-4 or regional lymph node-positive disease with positive mesorectal fascia (MRF) or T4b disease evaluated by pelvic MRI were randomly assigned to the SCPRT-boost group (25 Gy over 5 fractions plus 4 Gy delivered to the gross tumor volume, followed by four cycles of chemotherapy) or preoperative chemoradiotherapy group (50 Gy over 25 fractions with concurrent chemotherapy). Then, patients received total mesorectal excision surgery after preoperative treatment. The primary endpoint was the R0 resection rate. The interim analysis was performed when 42 patients completed their assigned treatments.
Results
From October 2018 to November 2019, a total of 43 patients were enrolled, and 42 patients were included in the interim analysis. During preoperative therapy, grade 3 or above toxicities were observed in 10/21 (47.6%) patients in the experimental group, and 4/21 (19.0%) patients in the control group. A total of 17 (81.0%) and 13 (61.9%) patients in the experimental group and control group underwent surgery, respectively. Overall, 69.7% of the patients achieved R0 resection or clinical complete response (cCR) in the intention-to-treat analysis. Surgery-related adverse complications were observed in 2 patients (11.8%) in the experimental group and 1 patient (7.7%) in the control group.
Conclusion
Our results show that the toxicity of an MRI simulation-guided boost dose after short-course preoperative radiotherapy (SCPRT) for unresectable rectal cancer is acceptable. Thus, this clinical trial will be continued as planned.
Publisher
Research Square Platform LLC