Lynch syndrome (LS) is a hereditary cancer syndrome that causes the majority of hereditary CRC and approximately 3% of all CRC. LS significantly increases the risk for an individual to develop CRC during their lifetime. Individuals with LS also have an increased risk to develop extracolonic cancers, including endometrial, gastric, ovarian, upper urinary tract, small bowel, biliary tract, CNS, and certain types of skin cancer. Given the hereditary nature of this syndrome, preventing second primary tumors in patients with Lynch Syndrome after surgery to the primary site is very important.~The purpose of this study is to prevent adenomatous polyps and second primary tumors using PD-1 antibody (Tripleitriumab) in patients with Lynch Syndrome.~The primary outcome of this study is the incidence of intestinal adenomatous polyps and secondary primary tumors. The secondary outcomes are the incidence of colorectal adenomatous polyps greater than 1cm, incidence of high-grade colorectal polyps, treatment-related adverse events, disease-free Survival and overall Survival.~There are two groups: the PD-1 antibody prevention group and the routine follow-up group. For the PD-1 antibody prevention group, participants will receive Toripalimab 240mg IV every 3 months for a year. For the routine follow-up group, there is no drug intervention.~This whole study will take 5 years: the first year for recruiting and the latter four years for follow-up.
This study aims to explore the role of PD-1 Antibody in preventing adenomatous polyps and second primary tumors in patients with Lynch Syndrome. There two arms, one is the experimental arm (PD-1 antibody prevention group) and the other is the control arm (routine follow-up group). For the experimental group, Tripleitriumab (PD-1 antibody) is given every 3 months for a year.