Colon Cancer

The colon, in four sections, makes up the majority of the 5-foot length of the large intestine. In the alimentary canal (the path that food follows through your body), the colon follows the small intestine and comes before the rectum. The colon is responsible for absorbing water, vitamins, and minerals from the intestinal contents and conserving them. It also mixes the intestinal contents, forms stools, and rids the body of undigested material.

Colon and rectum cancers are sometimes referred to together as “colorectal cancer” - in this article, they will be referred to as “colon cancer.” Together they are the third most common cancer in adults and the second leading cause of cancer deaths in men and women in the United States. Most cases of colon cancer begin with the development of benign polyps, finger-like growths that protrude into the intestinal cavity. These benign polyps are relatively common in people over age 50. They can become cancerous, though, with the ability to invade the normal colon and spread to other parts of the body (metastasize). The tumors can create blockages in the intestine, preventing elimination. As estimated by the American Cancer Society, about 50,000 Americans die from colon cancer each year, and approximately 149,000 new cases are diagnosed.

The exact causes of colon and rectal cancer are not known, but risk appears to be associated with genetic, dietary, and lifestyle factors. Those with a personal or family history of colon cancer or polyps are at a higher risk, as are those with ulcerative colitis, a form of inflammatory bowel disease, and immunodeficiency disorders. A rare inherited disease called familial adenomatosis or polyposis causes benign polyps to develop early in life and causes cancer in almost all affected persons unless the colon is removed. Risk also increases with age and with the occurrence of cancers in other parts of the body. High fat and meat diets are a risk factor, especially combined with minimal fruit, vegetable, and fiber intake. Lifestyle factors include cigarette smoking, obesity, and a sedentary lifestyle.

Symptoms

Colon cancer frequently develops without early signs or symptoms. Symptoms that can occur include:

* Diarrhea, constipation, or other changes in bowel habits lasting 10 days or more
* Blood in the stool (either bright red or dark in color)
* Unexplained anemia
* Abdominal pain and tenderness in the lower abdomen
* Abdominal discomfort (frequent gas pains, bloating, fullness, and cramps)
* Intestinal obstruction
* Weight loss with no known reason
* Stools narrower than usual
* Constant tiredness

These signs and symptoms can be caused by cancer or by a number of other conditions. It is important to talk to your doctor if you have any of these signs and symptoms and to screen for colon cancer even if you don't. If the polyps that lead to the cancer are detected and removed, colon cancer can often be prevented. If colon cancer is detected early, it is up to 90% curable.

Screening Tests for Early Detection

It is recommended that all adults begin regular colon cancer screening when they turn 50. Deciding which screening test to use and how often ultimately depends on a person's individual risk of colon cancer. If a first-degree relative has had colon cancer, for instance, screening should start 10 years prior to the age that relative was diagnosed to help identify possible pre-cancerous polyps.

In March 2008, screening guidelines for the early detection of pre-cancerous polyps and colon cancer were released jointly by the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. These guidelines divide screening options into two categories: 1) full or partial structural exams that inspect the colon itself and can detect both cancer and precancerous polyps and 2) laboratory tests on stool samples that detect blood that is possibly caused by existing cancer or detect cancerous cells shed in the stool. Another difference between these screening options is that direct examinations such as sigmoidoscopy and colonoscopy allow for removal of polyps at the time the test is done. All other tests must be followed up with another procedure to remove any suspected growths.

Treatment

All stages of colon cancer are usually treated by surgically removing the cancer and possibly some of the surrounding tissue. For Stages II and III, chemotherapy and/or radiation therapy may be added to help kill the cancer and shrink the tumor. Chemotherapy and radiation may also be used in Stage IV to improve symptoms and to prolong life. Biological therapy or immunotherapy, therapy that stimulates the patient’s immune system to recognize the cancer cells and fight them, may also be used in some cases.

source :http://www.labtestsonline.org/understanding/conditions/colon.html