Types of colorectal cancer
Adenocarcinomas make up 95 percent of all colorectal cancer cases. In the gastrointestinal tract, adenocarcinomas develop in the cells of the lining inside the colon and/or the rectum. They typically start as a growth of tissue called a polyp. A particular type of polyp called an adenoma may develop into cancer. Polyps are often removed during a routine colonoscopy before they may develop into cancer.
Of the rarer types of colorectal cancer, gastrointestinal carcinoid tumors grow slowly, form in the neuroendocrine cell and make up 1 percent of all colorectal cancers, whereas primary colorectal lymphomas develop in the lymphatic system and account for 0.5 percent of colorectal cancers. To learn more about these and other colorectal cancer types, explore the tabs to the left.