Standard Systemic Therapy Combined With High/Low-dose Radiotherapy Plus Toripalimab for Metastatic Colorectal Cancer

This study is testing whether adding a targeted radiation treatment (stereotactic body radiotherapy, SBRT) plus an immunotherapy drug (toripalimab) to standard chemotherapy can improve outcomes for patients with metastatic colorectal cancer. It focuses on a subtype of colorectal cancer (MSS/pMMR) that historically responds poorly to immunotherapy alone. **You may be eligible if...** - You are between 18 and 75 years old - You have confirmed metastatic colorectal cancer (the MSS/pMMR subtype) - You have at least one tumor site that can be treated with SBRT - You are starting first-line treatment OR your cancer has progressed after one round of treatment - Your blood counts, liver, and kidney function meet the required thresholds **You may NOT be eligible if...** - Your blood counts are too low (anemia, low platelets, or low white cells) - You have severe liver dysfunction or abnormal kidney function - You have active gastrointestinal ulcers, bleeding problems, or uncontrolled high blood pressure - You have had a recent blood clot, heart attack, or heart failure within the past 6 months - You have previously received immunotherapy (anti-PD-1 or anti-CTLA-4) - You have active hepatitis B or C - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.