Stereotactic Body Radiation Therapy for Unresectable Locally Recurrent Rectal Cancer: A Prospective, Single-arm, Phase II Study
Objective: R0 resection rate. Secondary
Objectives: 1-year local progression-free survival (LPFS) and overall survival (OS), 2-year LPFS and OS, and side effects of the treatment. Study
Design: A single-arm, open-label, prospective phase II study. Study Population and Expected Enrollment: Patients with unresectable locally recurrent rectal adenocarcinoma, with an expected enrollment of 20 patients. Scheduled Visits and Duration: December 2024 to November 2026. Trial Duration: December 2024 to November 2026. Intervention: SBRT for unresectable locally recurrent rectal cancer. Statistical Hypothesis: Enrolled patients are those with unresectable recurrent rectal cancer. Based on previous literature reports and retrospective clinical data from our center, it is hypothesized that the R0 resection rate for patients with unresectable locally recurrent colorectal cancer who do not receive SBRT is 20%, while the R0 resection rate for those receiving SBRT intervention is 50%. Using Simon's optimal two-stage study design, a single-arm study, with α set at 0.05 and 1-β at 0.80, and an expected loss to follow-up rate of 10%.
• Written informed consent;
• 18-75 years of age;
• Histologically, cytologically, or radiologically confirmed tumor recurrence, and the MDT assesses that the recurrent lesion cannot achieve R0 resection (unresectable defined as: 1) Pelvic MRI shows infiltration of S2 or above, 2) and/or lateral pelvic invasion, 3) and/or neurovascular invasion of the pelvic, 4) No indication for R0 resection after MDT discussion);
• No clear distant metastasis at the time of diagnosis of locally recurrent rectal adenocarcinoma or MDT assesses that oligometastatic lesions are resectable or controlable (UICC 8th edition);
• No previous radiotherapy for initial treatment, or more than 6 months between completion of initial radiotherapy and start of re-radiotherapy, with a previous radiotherapy dose of less than 50.4 Gy, and no grade 3-4 radiotherapy side effects in the small intestine or bladder;
• ECOG score for performance status is 0-1 (Appendix 1);
• Peripheral blood cell counts and liver and kidney function within the following acceptable ranges (tested within 15 days before treatment):
⁃ White blood cell count more than 3.0×10\^9/L or neutrophils more than 1.5×10\^9/L;
‣ Hemoglobin more than 80 g/L; ③ Platelets more than 100×10\^9/L; ④ ALT or AST less than 3 times the upper limit of normal; ⑤ Total bilirubin less than 1.5 times the upper limit of normal; ⑥ Creatinine less than 1.5 times the upper limit of normal;
• No history of other malignant tumors, non-pregnant or lactating patients, participants must use effective contraception during the study and for 6 months after the last treatment;
• Expected survival more than 12 months.