Lynch syndrome has a good prognosis. Lynch syndrome is an inherited disorder caused by mutations in mismatch repair genes and is an autosomal dominant disorder. Lynch syndrome is characterized by a higher risk of patients developing colon and rectal cancer and primary tumors elsewhere. Some patients may develop tumors only once in their lifetime, and most patients may develop primary tumors in multiple systems and organs. When a tumor is diagnosed in one area, even if the tumor can be cured in that area by surgery or other means, tumors in other areas may occur later. The reason for the high incidence but favorable prognosis of Lynch syndrome remains to be demonstrated. When Lynch syndrome is diagnosed, early and standardized treatment is recommended to minimize the adverse effects of the disease.