Light micrograph section through human tissue showing a benign adenomatous polyp of the large intestine. Adenomatous polyps (adenomas) of the colon and rectum are benign non-cancerous growths, but may be precursor lesions to colorectal cancer. Polyps greater that one centimetre in diameter are associated with a greater risk of cancer. If polyps are not removed, they continue to grow and become cancerous.