Diseases that may lead to colon cancer include: 1. inflammatory bowel disease: including ulcerative colitis and Crohn’s disease, among these two diseases, ulcerative colitis has a higher chance of malignant transformation into colon cancer compared with Crohn’s disease; 2. colonic adenoma: the larger the size of a single adenoma, the higher the possibility of malignant transformation; 3. familial adenomatous polyposis: patients generally have a family history of the disease among first-degree relatives, including siblings, parents with the disease. Patients with a family history of adenomatous polyposis have a higher chance of developing colon cancer. Patients with the above three conditions should be treated as early as possible to eliminate the disease in time to avoid its deterioration and the development of colon cancer.