Colon cancer is cancer of the large intestine (colon), the lower part of the digestive system. Rectal cancer is cancer of the last several inches of the colon. Together, they’re often referred to as colorectal cancers.
Most cases of colon cancer begin as small, noncancerous (benign) clumps of cells called adenomatous polyps. Over time some of these polyps become cancerous. Polyps may be small and produce few, if any, symptoms. For this reason, doctors recommend regular screening tests to help prevent cancer of colon by identifying polyps before they become colon cancer.
Signs and symptoms of this type of cancer include:
A change in bowel habits, including diarrhea or constipation or a change in the consistency of the stool
Rectal bleeding or blood in the stool
Persistent abdominal discomfort such as cramps, gas, or pain
A feeling that the bowel doesn’t empty completely
Weakness or fatigue
Unexplained weight loss
Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they’ll likely vary, depending on the cancer’s size and location in the large intestine.
If the symptoms of colon cancer are appearing, such as blood in the stool or a persistent change in bowel habits, make an appointment with your doctor. Talk to them about when to begin screening for colon cancer. Guidelines generally recommend cancer screenings begin at age 50. A doctor may recommend more frequent or earlier screening if there are other risk factors, such as a family history of the disease.
In most cases, it’s not clear what causes colon cancer. Doctors know that colon cancer occurs when healthy cells in the colon become altered. Healthy cells grow and divide in an orderly way to keep the body functioning normally, but when a cell is damaged and becomes cancerous, cells continue to divide — even when new cells aren’t needed. These cancer cells can invade and destroy normal tissue nearby, and can travel to other parts of the body.
By Khrystyana Kirton
Edited by Stephanie Dawson
Reviewed by Nima Shei MD