Colon cancer is cancer of the large intestine (colon), the lower part of your digestive system. Colon cancer is the second most common cancer in the USA with equal distribution between men and women. Colon cancer usually affects people over the age of 40, with the majority of people who are diagnosed with the condition being over 60 years of age. Colon cancer may affect any racial or ethnic group; however, some studies suggest that Americans of northern European heritage have a higher-than-average risk of colon cancer.

INCIDENCE

Colon cancer is more common in industrialized nations and in those societies where red meat is a major part of the diet, although evidence tends to suggest that merely changing your diet to white meat and seafood as in for instance Japan, tends to just swap stomach cancer for colon cancer. In almost all cases colon cancer is a treatable disease if caught early.

SIGNS AND SYMPTOMS

Colon cancer usually begins with the growth of benign growths such as polyps. Often there are no early symptoms. If signs and symptoms of colon cancer do appear, they may include: a change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool for more than a couple of weeks, rectal bleeding or blood in your stool, persistent abdominal discomfort, such as cramps, gas or pain, abdominal pain with a bowel movement, a feeling that your bowel doesn't empty completely, weakness or fatigue and unexplained weight loss.

CAUSES

Colon cancer's exact cause is unknown, but it appears to be influenced by both inherited and environmental factors. Studies show a concentration in areas of higher economic development suggesting a relationship to diet, particularly excess animal fat and low fiber. Other factors that increase the risk of developing colon cancer are: age over 40, the presence of other diseases of the digestive tract, family history and ulcerative colitis.

Development of colon cancer at an early age, or at multiple sites, or recurrent colon cancer, suggests a genetically transmitted form of the disease as opposed to the sporadic form. There also is a slight increased risk for colon cancer in the individual who smokes.

The most common colon cancer cell type is adenocarcinoma which accounts for 95% of cases.

DIAGNOSIS

The development of polyps of the colon usually precedes the development of colon cancer by five or more years. The American Gastroenterologial Association revised its screening guidelines in 2003 to recommend that people with two or more first-degree relatives with colorectal cancer or a first-degree relative with colon or rectal cancer before age 60 should have a screening colonoscopy beginning at age 40 or beginning 10 years prior to the age of the earlier colon cancer diagnosis in their family (whichever is earliest). Those with a first-degree relative diagnosed with colon cancer after age 60 or two second-degree relative with colon or rectal cancer should begin screening at age 40 with one of the methods listed above, such as annual sigmoidoscopy. The most common colon cancer screening tests are colonoscopy, sigmoidoscopy, and fecal occult blood test.

CT scans and Barium enemas are also routinely used for diagnosis of colon and rectal cancers.

TREATMENT

Almost all colon cancers are treated with surgery first, regardless of stage. The malignant tumor, adjacent tissues and any lymph nodes that may contain cancer cells are removed.

In colon cancer, chemotherapy after surgery is usually only given if the cancer has spread to the lymph nodes (Stage III). Radiation therapy may also be used to induce tumor regression. As with other cancer treatments, the incidence of side effects varies with patient health and the exact nature of the treatment.

PREVENTION

There is not an absolute method for preventing colon cancer. Still, there are steps an individual can take to dramatically lessen the risk or to identify the precursors of colon cancer so that it does not manifest itself. People who turn age 50, and all of those with a history of colon cancer in their families, should speak with their physicians about the most recent screening recommendations from physician and cancer organizations. They should watch for symptoms and attend all recommended screenings to increase the likelihood of catching colon cancer early. Exercise is believed to reduce the risk of colon cancer. Apparently, no association exists between frequency of bowel movement or laxative use and risk of colon cancer.

PROGNOSIS

Prognosis depends on the stage of the disease and the overall health of the patient. If diagnosed early, before the tumor has spread from the bowel, these treatments are very effective, with about 90% of patients alive five years after diagnosis. If the colon cancer does not come back (recur) within 5 years, it is considered cured. Prognosis is poor in patients with liver and lung metastases.