The Colon

The colon and the rectum make up the large intestine, the final segment of the digestive system. The colon is a tubular muscle, lined with a layer of mucous cells that help the chyme (food combined with the body’s digestive fluids) continue its journey through the bowel and out of the anus by lubricating the path. Glands resembling skin pores extract any water remaining in the food residue. The colon then moves rest of the waste material to the rectum in a process called peristalsis, involuntary wavelike contractions of the colon wall. The fecal matter is then stored in the rectum, until it is expelled out of the anus through a bowel movement.

Colon Cancer

Cancer of the colon is known as colorectal cancer. It almost always begins as an abnormal growth of tissue called an intestinal polyp, or adenoma. Over 95% of colorectal cancers are adenocarcinomas that develop from a mutation in the cells lining the wall of the colon and/or rectum. The risk factors are:

• A history of ulcers in the large intestine
• History of colon, ovarian, rectal, endometrial, or breast cancer.
• Hereditary nonpolyposis colon cancer (HNPCC)
• Family history of colon cancer
• 50 years of age or more

Symptoms

Unfortunately, most people who have colon cancer have either very nonspecific symptoms or none at all; unless the cancer has become advanced, at which point any or all of the following symptoms may appear:

• Bloody and/or narrow stools
• Diarrhea
• Constipation
• Weight loss
• Fatigue
• Vomiting
• Gas pains and bloating
• Bowels do not feel empty after expelling waste.

Tumors in the ascending colon are able to grow unhindered because the stool in the ascending colon is very nearly liquid and is not obstructed by the growths. Symptoms of blocked bowel movements tend to show up first in the descending colon because the stool is more solid there.