Colon Cancer (also called colorectal or large bowel cancer) refers to cancerous growths in the colon and the rectum. It is the third leading cause of cancer in males and the fourth leading cause of cancer in females globally, and according to the World Health Organization (WHO) results in 655,000 deaths world wide per year. (Lee, 2007; WHO Fact-sheet on Cancer, 2006) This paper gives general information about colon cancer including its signs and symptoms, causes / risk factors, diagnosis, prevention, and treatment.

Signs and Symptoms

There are little or no symptoms of colon cancer in its early stage in most cases and the disease can be present for several years before symptoms develop. However, when symptoms do appear, they are often nonspecific and vary according to where the cancerous tumor is located in the bowel. Some typical symptoms include:

Change in Bowel Habits: A change in one's bowel habits, including constipation, diarrhea or narrow stools for more than a couple of weeks be a possible sign of colon cancer. This is because a tumor at the far end of the colon or the rectum could cause an obstruction for the stool to come out easily; thus causing constipation. Such obstruction may also lead to narrow stools as the waste material attempts to maneuver around the tumor (Myers, 2008).

Abdominal Pain and Cramps: Tumors may result in bowel obstruction, which causes a blockage for solids, liquids, gas, or blood flow to the colon. This may cause pain and abdominal. Perforation of the tumor through the bowel walls also occurs occasionally.

Blood in Stools Bleeding from the tumors result in the presence of blood in stool. If the tumor is located at the beginning of the colon, the blood would be dry and make the stool black; it may not be even noticeable if the bleeding is slight. On the other hand, if the tumor is located in the rectum or toward the end of the colon, it may be bright red.

Weakness and Lethargy Persistent bleeding may lead to iron deficiency (anemia) that causes extreme lethargy and weakness -- a result of lack of oxygen supply to body cells since iron in blood transports the oxygen.

Unexplained Weight Loss Even though most of us would be happy to lose a few pounds without a painful effort, unexplained weight loss is usually a warning sign by our bodies that something is wrong. It occurs in people suffering from colon cancer because a tumor releases chemicals that increase their metabolism.

Nausea and Vomiting Nausea and vomiting is usually the result of less harmless reasons such as motion sickness, an unpleasant sight or smell, common viruses, and too much alcohol. It can also be the result of colon cancer.

Sense of Fullness / Bloating: A tumor at the end of the colon or in the rectum may cause a sense of fullness, giving one the feeling of not being fully relieved even after having a bowel movement.

Causes / Risk Factors

Cancer is not contagious, i.e., people cannot 'catch' cancer from others. There are, however, certain risk factors that increase one's chances of getting colon cancer. Some of these are described below:

High Fat Diet: Research has shown that colon cancer is more common in countries with high fat intake. It is believed that break-down of fat in the body (fat metabolism) produces cancer causing chemicals (carcinogens). Conversely, high fiber diets help to reduce the risk

History of colon polyps: It has been found that a majority of colon cancers develop from colon polyps. Growths in the inner lining of the large intestine and the rectum are quite common. These polyps are mostly benign and can be easily removed easily. If left untreated, the benign colon polyps can become cancerous.

Genetic Reasons: People with a family history of colon cancer are also prone to the disease. If you have a parent or a sibling with the disease, your chances of developing colon cancer is high; the risk is even greater if more than one family member has colon or rectal cancer ("Colon Cancer" Mayo Clinic, 2008). Among close relatives of colon cancer patients, the lifetime risk of developing colon cancer is 18%, which a threefold increase over the general population in the U.S. (Lee, 2007)

Ulcerative Colitis: Long-standing ulcers of the colon and Cohn's disease may ultimately develop into colon cancer.

Sedentary Lifestyle: Inactivity that causes waste to stay longer in the colon is believed to increase the risk for developing colon cancer. Obese people are also prone to the disease.

This may be because when you're inactive, waste stays in your colon longer. Getting regular physical activity may reduce your risk

Diagnosis

When colon cancer is suspected, barium enema x-ray or colonoscopy is usually performed to confirm the diagnosis and to find out the exact location of the tumor. For the barium enema x-ray, the patient is given an enema with white chalky liquid containing barium; it helps to outline the large intestine, and the tumors are then detectable as dark shadows on the x-rays. Colonoscopy consists of a procedure in which a long flexible tube is inserted via the rectum for inspecting the inside of the colon. If colon polyps are found, they are removed through the colonoscope and examined in the lab for cancer and for pre-cancerous growth ("Colon Cancer" Mayo Clinic, 2008).

If cancer is confirmed through biopsy of tissues obtained during colonoscopy, further 'staging' tests such as chest x-rays, ultrasonography, and CT scan of the lungs, liver, and abdomen are carried out, to determine whether the colon cancer has spread to other parts of the body. Blood test for CEA (carcinoembryonic antigen) may also be done in some cases (Ibid.)

Prevention

Early Detection: Early detection of colon polyps and their removal is perhaps the most effective preventive measure since a majority of colon cancers develop from benign colon polyps that turn cancer over a long period. Even if cancer has already developed, its early removal before it spreads to other parts of the body, improves the chances for survival of the patient. (Lee, 2007; "Colon Cancer," 2008)

Regular Screening: The U.S. Multi-society Task Force on Colorectal Cancer recommends that regular screening for colon cancer should begin at age 50 for all people with an average risk for the disease. The suggested screening tests include annual fecal occult blood testing, sigmoidoscopy every 5 years, barium enema test every 5 years, and colonoscopy every 5 years.

Diet: A high fiber diet including fruits, vegetables and whole grains containing vitamins, minerals, and anti-oxidants play an important role in prevention of all types of cancer. Avoiding saturated fats, red meats, alcohol and smoking also helps.

Exercise: Physical activity helps to reduce weight and the time waste material stays in the colon -- both of which are believed to be colon cancer risks.

Preventive Drugs: Drugs such as aspirin and other non-steroidal anti-inflammatory drugs are known to reduce the risk for colon cancer. However, such drugs have side-effects such as ulcers and gastro-intestinal bleeding.

Treatment

Surgery: This is the most common treatment and is performed in all stages of colon cancer. If the cancer is detected at an early stage, a local excision -- removing the cancer without cutting through the abdominal wall -- or a polypectomy -- removal of the polyp -- may be enough. If the cancer is larger, resection or a partial colectomy is performed. In this procedure, part of the colon containing cancer and a small amount of healthy surrounding tissue is removed and the cut ends of the colon are joined together. If sewing together of the colon is not possible, a colostomy is also performed to make an opening outside of the body for the waste to pass through. ("Colon Cancer Treatment" National Cancer Institute)

Chemotherapy: It is a cancer treatment that uses drugs to stop the growth of cancer cells by killing the cells or by stopping them from dividing. Chemotherapy drugs are taken orally or through injections. Chemotherapy is usually used after surgery to control recurrence of the cancer. It is also used when the cancer has spread beyond the colon area.

Radiation Therapy: The treatment uses high energy x-rays and other radiations to kill cancer cells or to keep them from growing. Radiation therapy may be of external type that uses a machine placed outside the body to send radiation to the cancer or internal type that uses a radioactive substance sealed in needles, wires, or catheters and placed near the cancer. It is used to kill cancer cells that might remain after surgery, to shrink large tumors before an operation, or to relieve symptoms of colon cancer and rectal cancer.

Immunotherapy: It is a treatment that uses the body's immune system to fight cancer. In this type of treatment drugs as well as substances made by the body itself are used to boost, and/or restore the body's natural defenses against cancer.

References

Cancer." (2006). WHO Fact Sheet No. 297. Retrieved on February 27,…