Colorectal cancer usually starts in the glands of the colon or rectum lining. Almost all cases of colorectal cancer begin as non-cancerous (benign) polyps that slowly develop into cancer. Like many cancers, colorectal cancer can spread to lymph nodes or other organs. Colorectal cancer symptoms may include: blood in stool, changes in bowel habits, pelvic pain, narrow stools, and unexplained weight loss.
Colorectal cancer affects nearly 1.3 million people worldwide each year and is the fourth most common cause of cancer death.