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Colon Cancer

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Please check out the Colonoscopy song written by Peter Yarrow of Peter, Paul and Mary. Used with permission from Peter. http://youtu.be/JqvpfrnmJrg

What is Colon or Colorectal Cancer?

Colorectal cancer is cancer that occurs in the large intestine and rectum. The colon is a muscular tube that is about five feet long. It absorbs water and nutrients from food. The rectum, the lower six inches of the digestive tract, serves as a holding place for stool, which then passes out of the body through the anus.

This year, about 148,000 people in the United States will be diagnosed with colorectal cancer. Although many people think of colorectal cancer as a disease that primarily affects men, it is slightly more common in women. Today, the average person has about a 1 in 20 chance of developing colorectal cancer during his or her life.

How Colorectal Cancer Develops

The colon is divided into four sections: the ascending colon, transverse colon, descending colon, and sigmoid colon. Most colorectal cancers arise in the sigmoid colon — the portion just above the rectum. They usually start in the innermost layer and can grow through some or all of the several tissue layers that make up the colon and rectum. The extent to which a cancer penetrates the various tissue layers determines the stage of the disease. Most colorectal cancers grow slowly over a period of several years, often beginning as small benign growths called polyps. Removing these polyps early, before they become malignant, is an effective means of preventing colorectal cancer.

Types of Colorectal Cancer

More than 95 percent of colorectal cancers are adenocarcinomas — cancers of the cells that line the interior of the colon and rectum. Rarer types of tumors include carcinoid tumors, gastrointestinal stromal tumors, and lymphomas. These latter types are reviewed elsewhere.

Common signs and symptoms of colorectal cancer

Colorectal cancer does not usually produce symptoms early in the progress of the disease. Symptoms are dependent upon the site of the primary tumor. Here are the typical symptoms:

  • bright red or very dark blood in the stool
  • a change in the frequency of bowel movements
  • constipation, or a feeling that the bowel doesn’t empty completely
  • stools that are narrower than usual
  • general abdominal discomfort, such as frequent gas pains, bloating, and/or cramps
  • weight loss with no known reason
  • constant tiredness
  • vomiting

Additional Cancer Resources

The above information is a condensed version of the information available at the Memorial Sloan Kettering website. Additional reliable Colon Cancer information can be found at the following websites:

American Society of Clinical Oncology

US National Cancer Institute