Colon cancer, also known as colorectal cancer, is cancer that starts in the colon or rectum.

Cancer is characterized by the abnormal, out-of-control growth of cells. Colon cancer occurs when healthy colon cells begin to grow uncontrollably.

The colon and rectum are part of the digestive system.

The colon is the large intestine, and the rectum is a passageway connecting the colon to the anus. (The rectum is also considered the final section of the colon.)

More than 95 percent of colon cancer cases can be classified as adenocarcinomas, which start in cells that produce a lubricating mucus in the colon and rectum, according to the American Cancer Society (ACS).

 

Prevalence

In 2015, there will be an estimated 132,700 new cases of colon cancer in the United States, 39,610 of which will occur in the rectum, according to the ACS.

Overall, it’s the fourth most common cancer in the country — behind breast cancer, lung cancer, and prostate cancer  (which affects only men) — and the third most common cancer in both men and women, according to data from the National Cancer Institute (NCI).

Colon cancer makes up about 8 percent of all new cancer cases in the United States.

There were an estimated 1,168,929 people living with colon cancer in the country in 2012, according to NCI data.

Causes and Risk Factors

Exactly what causes cells in the colon to grow uncontrollably is unknown in most cases.

Cells often change due to genetic mutations, which can be either inherited from your parents or acquired through environmental factors.

An inherited or acquired mutation to the APC gene, which normally keeps cell growth in check, is thought to cause some cases of colon cancer.

Regardless of the biological mechanisms involved, various risk factors are associated with colon cancer, including:

• Smoking
• Being older than 50
• Following a diet high in red meat and processed meats, a diet low in fruits and vegetable, or a diet low in fiber and high in fat.
• Drinking alcohol havily
• Having an inflammatory bowel disease, such as crohn’s disease.
• Having a personal or family history of colon cancer or colorectal polyps (abnormal growths in the colon)
• Being of African descent
• Having type 2 diabetes
• Having certain rare genetic syndromes, such as familial adenomatous polyposis, Lynch syndrome (hereditary non-polyposis colon cancer), Turcot syndrome, Peutz-Jeghers syndrome, or MUTYH-associated polyposis.

Colon Cancer Prevention

To lower your risk of getting colon cancer, you can avoid certain risk factors with healthy behaviors such as the following:

 Do not smoke: Although you may think of smoking as damaging to the heart and lungs, smoking also increases the risk of developing colon cancer and dying from it.

Be physically active: Individuals who are physically fit have a lower risk of colorectal cancer compared to those with a sedentary lifestyle.

Eat a healthy, well-balanced diet: A diet high in fruits and vegetables appears to reduce the risk of colon cancer by about half, compared to a diet deficient in produce.

Cruciferous vegetables such as cabbage, broccoli, cauliflower, and Brussels sprouts are especially beneficial.

Decrease the amount of red meat in your diet, and cut back on meats that are cooked at high temperatures — such as fried, grilled, and broiled meats — as these may increase the risk of colon and rectal cancers.

Take daily NSAIDs: Low daily doses of aspirin  may reduce your colon cancer risk, but talk to your doctor first to determine if this is a good strategy for you.

Don’t ignore any symptoms: Colon cancer symptoms include change in your bowel movements (including change in the shape or color of the stool), discomfort when having a bowel movement, cramping in your lower abdomen, frequent gas pains, losing weight without dieting, and constant fatigue.

See your doctor if you experience any of these symptoms for more than a few days.

Know your health history: You’re at increased risk for colorectal cancer if you have a history of colon cancer or precancerous polyps.

Other factors that increase your risk include a family history of one or more parents, siblings, or children with colorectal cancer or precancerous polyps; a family history of multiple cancers involving the uterus, ovary, breast, and other organs; and a personal history of inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease.

Getting regular colon cancer screening tests after age 50 can also effectively prevent colon cancer.

These tests allow doctors to detect and remove colorectal polyps before they become cancerous — it takes 10 to 15 years for new polyps to turn into cancer, according to the ACS.

Colon cancer screening tests — which include colonoscopies and stool tests, among others — can also detect colon cancer early when it’s highly treatable