Stereotactic Body Radiation Therapy for Unresectable Locally Recurrent Rectal Cancer: A Prospective, Single-arm, Phase II Study
Objective: 1-year local progression-free survival (LPFS) . Secondary
Objectives: R0 resection rate 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 40 patients. Scheduled Visits and Duration: December 2024 to November 2027. Trial Duration: December 2024 to November 2027. 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 1-year LPFS for patients with unresectable locally recurrent colorectal cancer who do not receive SBRT is 20%, while the 1-year LPFS for those receiving SBRT intervention is 40%. 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.