Colon cancer is a type of cancer that begins in the large intestine (colon). The colon is the final part of the digestive tract.
Colon cancer typically affects older adults, though it can happen at any age. It usually begins as small, noncancerous (benign) clumps of cells called polyps that form on the inside of the colon. Over time some of these polyps can become colon cancers.
Polyps may be small and produce few, if any, symptoms. For this reason, doctors recommend regular screening tests to help prevent colon cancer by identifying and removing polyps before they turn into cancer.
Colon cancer is sometimes called colorectal cancer, which is a term that combines colon cancer and rectal cancer, which begins in the rectum.
Most people who are diagnosed with colon cancer have a type called adenocarcinoma. There are other rarer tumor types too. These other types of colon cancer may be treated differently than adenocarcinoma. The section of this guide on the diagnosis and treatment of colon cancer refers primarily to adenocarcinoma.
Learn more about the types of colon cancer below.
The vast majority of colon cancer is adenocarcinoma. This is a cancer of the cells that line the inside surface of the colon.
Carcinoid tumors start in hormone-producing cells in the intestines.
Gastrointestinal stromal tumors can be a type of soft tissue sarcoma that can be found anywhere in the gastrointestinal tract but is rare in the colon. These tumors can also be other types of sarcoma that start in the blood vessels or connective tissue of the colon.
Lymphoma is a cancer of the immune system. It more commonly starts in the lymph nodes but can start in the colon.
About 5 to 10 percent of people get colorectal cancer because of specific mutations in the genes that are passed from parents to children, which are referred to as hereditary. MSK’s colon cancer experts may offer you genetic testing to see if you have hereditary mutations in your genes that can increase your cancer risk. Whether you should have this testing is based on an assessment of your personal risk. Learn more about genetic testing for colon cancer and the types of hereditary conditions that often lead to the disease.
Signs and symptoms of colon cancer include:
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 your large intestine.
Colonoscopy is a procedure where a long flexible tube with camera on one end is inserted to inspect the inside of the colon, if some abnormal tissues are found they are removed and sent to pathologist for biopsy to detect any cancer.
Barium Enema is a procedure in which liquid solution containing barium element is injected into colon through rectum followed by an x-ray of the colon and rectum is taken to detect tumors and polyps.
Treatment of colon cancer depends on the type of cancer, stage of cancer, age, health status and other important additional personal characteristics. Most common options for colon cancer are surgery chemotherapy and radiation therapy.
Surgery is done in some cases of colon cancer to remove part or entire colon is called colectomy. In some cases nearby lymph nodes are also usually removed depending spread of the cancer tissues.
Chemotherapy is given in which chemicals or medications that interfere with the cell division process damaging proteins or DNA so that cancerous cells are damaged and die. The chemotherapy treatments are given in cycles so that the body has the time to heal in between the doses.
Radiation is given focusing high energy rays on the cancer cells causing damage to the molecules that make up the cancer cells to prevent their further growth.
In general, colon cancer begins when healthy cells in the colon develop changes (mutations) in their DNA. A cell's DNA contains a set of instructions that tell a cell what to do.
Healthy cells grow and divide in an orderly way to keep your body functioning normally. But when a cell's DNA is damaged and becomes cancerous, cells continue to divide — even when new cells aren't needed. As the cells accumulate, they form a tumor.
With time, the cancer cells can grow to invade and destroy normal tissue nearby. And cancerous cells can travel to other parts of the body to form deposits there (metastasis).
Factors that may increase your risk of colon cancer include:
Older age. Colon cancer can be diagnosed at any age, but a majority of people with colon cancer are older than 50. The rates of colon cancer in people younger than 50 have been increasing, but doctors aren't sure why.
African-American race. African-Americans have a greater risk of colon cancer than do people of other races.
A personal history of colorectal cancer or polyps. If you've already had colon cancer or noncancerous colon polyps, you have a greater risk of colon cancer in the future.
Inflammatory intestinal conditions. Chronic inflammatory diseases of the colon, such as ulcerative colitis and Crohn's disease, can increase your risk of colon cancer.
Inherited syndromes that increase colon cancer risk. Some gene mutations passed through generations of your family can increase your risk of colon cancer significantly. Only a small percentage of colon cancers are linked to inherited genes. The most common inherited syndromes that increase colon cancer risk are familial adenomatous polyposis (FAP) and Lynch syndrome, which is also known as hereditary nonpolyposis colorectal cancer (HNPCC).
Family history of colon cancer. You're more likely to develop colon cancer if you have a blood relative who has had the disease. If more than one family member has colon cancer or rectal cancer, your risk is even greater.