Unresectable Locally Recurrent Rectal Cancer

This is a prospective study to delve into the therapeutic benefits of combining stereotactic body radiation therapy (SBRT) with PD-1 monoclonal antibody treatment for patients with unresectable locally recurrent rectal cancer (ULRRC). Our aim is to ascertain the safety of this approach and to offer robust, evidence-based medical guidance for the management of ULRRC using this innovative combination therapy. Researchers will combine SBRT with PD-1 for ULRRC to see if this treatment can provide a benefit of survival. Participants will: 1. Receive chemotherapy combined with PD-1 therapy for 1 cycle → SBRT treatment → Chemotherapy combined with PD-1 therapy for 3-6 cycles (assessment 6 weeks after SBRT treatment) → Surgery/Maintenance therapy. 2. Visit the clinic once every 3 months for checkups and tests

Research Objectives and Principles: Through a prospective study, explore the effectiveness and safety of stereotactic body radiation therapy (SBRT) in the treatment of unresectable locally recurrent rectal cancer (ULRRC), providing high-level evidence for the use of SBRT in ULRRC treatment. Primary 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%.