How does colon cancer begin?

Polyps.: Polyps (adenomas) are small, benign masses that can form within the colon. The life cycle of the mucus membranes of the colon becomes disrupted, either from genetic or environmental reasons, causing growth of polyps. If polyp growth continues abnormally, they have the potential to develop into an invasive lesion and become cancerous.

Polyps: Generally, colorectal cancer develops from colorectal polyps. Most polyps do not cause symptoms that is why colonoscopy is one on asymptomatic patients to find polyps, remove hem, and prevent colon cancer.