Colon Cancer

Colon Cancer Information: Symptoms, Causes and Risk Factors Image

Colorectal cancer (CRC), also known as colon or bowel cancer, is a cancer of the large intestine (the colon), or the rectum (the lowest part of the large intestine).

If the disease occurs in the colon, it is usually called “colon cancer.” When it occurs in the rectum it is called “rectal cancer.” The term “colorectal cancer” is sometimes used to describe cancer of either the colon or the rectum.


Not counting skin cancers, CRC is the third most commonly diagnosed cancer in both men and women in the United States. It is also the second most common cause of death from cancer in U.S.

According to the American Cancer Society, an estimated 105,500 new cases of colon cancer will be diagnosed in 2003, in a ratio of 46.44 percent men to 53.55 percent women. The ACS also predicts around 42,000 new cases of rectal cancer, in a ratio of 56.67 percent men to 43.33 percent women.

Important Colorectal Cancer Information

  • Approximately ninety percent of people diagnosed with the condition are over the age of fifty.
  • Research indicates that the use of screening tests could help prevent death in as many as ninety percent of all cases.
  • Up to the age of fifty, occurrence of the disease is nearly the same among men and women; after fifty, it is slightly higher among men.
  • Women over the age of 75 are more likely to die of colon cancer than breast cancer.
  • Despite available screening, fewer than half of people aged fifty or older have had a fecal occult blood test (FOBT) within the previous five years.
  • As few as 37 percent of cases are diagnosed in the early stages, before the cancer has metastasized (spread) to other parts of the body.
  • One in seventeen men and one in eighteen women in the United States can expect to get CRC, during their lifetime.

Survival Rates

Although the number of deaths from CRC has decreased over the past fifteen years, experts estimate that about 57,100 US citizens (49.56 percent men to 50.44 women), will die from the disease, in 2003.

In cases of early detection where malignant cells are still localized in the colon, rectum or anus, CRC has a five-year survival rate as high as ninety percent. The five- year survival standard is defined as the percentage of people who survive at least five years after diagnosis. This definition does not include those who die from other diseases.

Once it has spread to other parts of the body, the rate drops to 65 percent. In cases where it has spread to remote organs, in particular the lungs, esophagus, liver or uterus, the five-year survival rate is as low as nine percent.

Many patients, however, survive for more than five years and this is particularly true of those people who have been recently diagnosed with the disease.

From Polyp to Cancer

CRC develops from abnormal cells. The disease progresses according to a sequence referred to by oncologists as “the adenoma-carcinoma sequence.”

What is a polyp?

A “polyp” is a grape-like growth that forms on the inner wall of the colon, rectum or anus. Polyps may be harmless or pre-cancerous and may take several years to develop. Chronic blood loss from polyps can lead to fatigue as a result of anemia. Polyps are uncommon in people under the age of fifty.

Research conducted by The National Cancer Institute indicates that CRC tends to develop gradually from benign, non-cancerous polyps in the intestine called “adenomatous polyps.” Small adenomatous polyps are common in people over the age of fifty. Adenomas typically develop on the surface lining of the large intestine, the colon, rectum or the anus. It is common for polyps to bleed. In fact, the fecal occult blood test is a screening method used to detect traces of blood, which may indicate the presence of polyps.

Studies have shown that certain types of polyps increase a person’s risk of developing CRC and that removal of polyps can help prevent the disease.

Who is Mainly at Risk

Anyone may develop the disease, at any age. However, research has identified a hereditary link with an increased occurrence of CRC. Also, if you are aged fifty or over, or have a family history with one or both parents or siblings who have had the disease, seeking screening for the condition is strongly advised. Those who have any of the other most common colon cancer risk factors should also consult a doctor about screenings.

An oncologist-a physician who specializes in treating cancerous tumors-or a gastroenterologist-a physician who specializes in digestive diseases-can advise you about available screening procedures and what to expect.

The Gastrointestinal System and CRC

The gastrointestinal tract, also known as the digestive system, includes the esophagus, stomach, small intestine, large intestine (colon or bowel), rectum and anus.

The colon is located at the end of the digestive system. Its main function is to process and store any waste products that remain when food has been digested and absorbed by the small intestine. The colon functions by absorbing water and reducing the bulk of waste that is eliminated in the stool, via the rectum and anus.

Studies have shown that diet may play an important role in the development (and prevention) of CRC.