Colon Cancer and Rectal Cancer

The colon and rectum are parts of the body's digestive system, which removes nutrients from food and stores waste until it passes out of the body. Together, the colon and rectum form a long, muscular tube called the large intestine (also called the large bowel). The colon is the first 6 feet of the large intestine, and the rectum is the last 8 to 10 inches.

Understanding Colorectal Cancer

Cancer that begins in the colon is called colon cancer, and cancer that begins in the rectum is called rectal cancer. Cancers affecting either of these organs may also be called colorectal cancer.

Colorectal Cancer: Who's at Risk?

The exact causes of colorectal cancer are not known. However, studies show that the following risk factor increase a person's chances of developing colorectal cancer:

• Age.Colorectal cancer is more likely to occur as people get older. This disease is more common in people over the age of 50. However, colorectal cancer can occur at younger ages, even, in rare cases, in the teens.
• Diet. Colorectal cancer seems to be associated with diets that are high in fat and calories and low in fiber. Researchers are exploring how these and other dietary factors play a role in the development of colorectal cancer.
• Polyps. Polyp are benign growths on the inner wall of the colon and rectum. They are fairly common in people over age 50. Some types of polyps increase a person's risk of developing colorectal cancer. A rare, inherited condition, called familial polyposis, causes hundreds of polyps to form in the colon and rectum. Unless this condition is treated, familial polyposis is almost certain to lead to colorectal cancer.
• Personal medical history. Research shows that women with a history of cancer of the ovary, uterus, or breast have a somewhat increased chance of developing colorectal cancer. Also, a person who has already had colorectal cancer may develop this disease a second time.
• Family medical history. First-degree relatives (parents, siblings, children) of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves, especially if the relative had the cancer at a young age. If many family members have had colorectal cancer, the chances increase even more.
• Ulcerative colitis. Ucerative colitis is a condition in which the lining of the colon becomes inflamed. Having this condition increases a person's chance of developing colorectal cancer.

Risk Factors Associated with Colorectal Cancer

• Age
• Diet
• Polyps
• Personal History
• Family History
• Ulcerative Colitis

Having one or more of these risk factors does not guarantee that a person will develop colorectal cancer. It just increases the chances. People may want to talk with a doctor about these risk factors. The doctor may be able to suggest ways to reduce the chance of developing colorectal cancer and can plan an appropriate schedule for checkups.

Colorectal Cancer: Reducing the Risk

Research shows that colorectal cancer develops gradually from benign polyps. Early detection and removal of polyps may help to prevent colorectal cancer. Studies are looking at smoking cessation, use of dietary supplements, use of aspirin or similar medicines, decreased alcohol consumption, and increased physical activity to see if these approaches can prevent colorectal cancer. Some studies suggest that a diet low in fat and calories and high in fiber can help prevent colorectal cancer.

Researchers have discovered that changes in certain genes (basic units of heredity) raise the risk of colorectal cancer. Individuals in families with several cases of colorectal cancer may find it helpful to talk with a genetic counselor. The genetic counselor can discuss the availability of a special blood test to check for a genetic change that may increase the chance of developing colorectal cancer. Although having such a genetic change does not mean that a person is sure to develop colorectal cancer, those who have the change may want to talk with their doctor about what can be done to prevent the disease or detect it early.

Detecting Cancer Early

People who have any of the risk factors described should ask a doctor when to begin checking for colorectal cancer, what tests to have, and how often to have them. The doctor may suggest one or more of the tests listed below. These tests are used to detect polyps, cancer, or other abnormalities, even when a person does not have symptoms. Your health care provider can explain more about each test.

• A fecal occult blood test (FOBT) is a test used to check for hidden blood in the stool. Sometimes cancers or polyps can bleed, and FOBT is used to detect small amounts of bleeding.
• A sigmoidoscopy is an examination of the rectum and lower colon (sigmoid colon) using a lighted instrument called a "sigmoidoscope".
• A colonoscopy is an examination of the rectum and entire colon using a lighted instrument called a colonoscope.
• A double contrast barium enema (DCBE) is a series of x-rays of the colon and rectum. The patient is given an enema with a solution that contains barium, which outlines the colon and rectum on the x-rays.
• A digital rectal examination (DRE) is an exam in which the doctor inserts a lubricated, gloved finger into the rectum to feel for abnormal areas.

Recognizing Symptoms

Common signs and symptoms of colorectal cancer include:

• A change in bowel habits
• Diarrhea, constipation, or feeling that the bowel does not empty completely
• Blood (either bright red or very dark) in the stool
• Stools that are narrower than usual
• General abdominal discomfort (frequent gas pains, bloating, fullness, and/or cramps)
• Weight loss with no known reason
• Constant tiredness
• Vomiting

These symptoms may be caused by colorectal cancer or by other conditions. It is important to check with a doctor.

Diagnosing Colorectal Cancer

To help find the cause of symptoms, the doctor evaluates a person's medical history. The doctor also performs a physical exam and may order one or more diagnostic tests.

• X-ray of the large intestine, such as the DCBE, can reveal polyps or other changes.
• A sigmoidoscopy lets the doctor see inside the rectum and the lower colon and remove polyps or other abnormal tissue for examination under a microscope.
• A colonoscopy lets the doctor see inside the rectum and the entire colon and remove polyps or other abnormal tissue for examination under a microscope.
• A polypectomy is the removal of a polyp during a sigmoidoscopy or colonoscopy.
• A biopsy is the removal of a tissue sample for examination under a microscope by a pathologist to make a diagnosis.

Stages of Colorectal Cancer

If the diagnosis is cancer, the doctor needs to learn the stage (or extent) of disease. staging is a careful attempt to find out whether the cancer has spread and, if so, to what parts of the body. More tests may be performed to help determine the stage. Knowing the stage of the disease helps the doctor plan treatment. Listed below are descriptions of the various stages of colorectal cancer.

• Stage 0. The cancer is very early. It is found only in the innermost lining of the colon or rectum.
• Stage I. The cancer involves more of the inner wall of the colon or rectum.
• Stage II. The cancer has spread outside the colon or rectum to nearby tissue, but not to the lymph node. (Lymph nodes are small, bean-shaped structures that are part of the body's immune system.)
• Stage III. The cancer has spread to nearby lymph nodes, but not to other parts of the body.
• Stage IV. The cancer has spread to other parts of the body. Colorectal cancer tends to spread to the liver and/or lungs.
• Recurrent. Recurrent cancer means the cancer has come back after treatment. The disease may recur in the colon or rectum or in another part of the body.

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