Colorectal Cancer

It's the type of cancer no one wants to talk about. But according to the American Cancer Society (ACS), cancers of the colon and rectum are among the most common cancers in the United States. (Read about "Cancer: What It Is") They occur in both men and women and are most often found in people who are over fifty years of age.

The colon and rectum make up the large intestine. During digestion, the colon removes nutrients from food and stores waste until the waste matter passes out of the body. (Read about "Digestive System") Cancers that occur in either part of the large intestine are termed colorectal cancer.

Risk factors

It was originally thought that a diet low in fiber put you at a higher risk. But, according to the National Institutes of Health, recent studies have shed some doubt on this theory, although research continues. (Read about "Fiber and Health") However, the American Medical Association (AMA) says that other lifestyle factors have been linked with a higher risk, including a diet high in fat, calories and alcohol, as well as smoking and obesity. (Read about "Quit Smoking" "Obesity")

According to the National Cancer Institute (NCI), other known risk factors include the following:

• Colorectal cancer is more likely to occur as we get older, although it can occur in young people as well.
• The presence of certain types of polyps (Read about "Colon Polyps"), or benign growths, on the inner wall of the colon or rectum, can indicate an increased risk. In particular, a hereditary condition called familial polyposis, in which hundreds of polyps form, is considered an important risk factor.
• Having a personal history of colorectal cancer or certain other types of cancer can put you at a higher risk.
• Having someone in your family who's been diagnosed with colorectal cancer can put you at a higher risk. (Read about "Family Health History")
• Having a condition called ulcerative colitis (Read about "Ulcerative Colitis") in which the lining of the colon becomes inflamed also increases your risk.

Reducing your risk

According to NCI, studies are now underway looking into a number of potential ways to reduce the risk of developing colorectal cancer. Among the things being examined are smoking cessation, use of dietary supplements, use of aspirin, decreased alcohol consumption and increased physical activity.

Until the results of such studies are known, the strongest weapon against colorectal cancer is early detection. Therefore, it's important to know the warning signs of colorectal cancer. ACS says these include:

• changes in bowel habits
• changes in the stool
• blood in the stool (Read about "Gastrointestinal Bleeding")
• vomiting
• abdominal discomfort, bloating or cramps
• unexplained weight loss or excessive fatigue

If you notice such changes, see your doctor right away.

Tests and staging

ACS, the American College of Radiology, and the U.S. Multi-Society Task Force on Colorectal Cancer (a group that comprises representatives from the American College of Gastroenterology, American Gastroenterological Association, and American Society for Gastrointestinal Endoscopy) have endorsed the following tests.

Tests that detect polyps and cancer:

• Colonoscopy every 10 years
• Flexible sigmoidoscopy every 5 years
• Double contrast barium enema (DCBE) every 5 years
• CT colonography (CTC) every 5 years

Tests that primarily detect cancer:

• Annual guaiac-based fecal occult blood test (gFOBT) with high test sensitivity for cancer
• Annual fecal immunochemical test (FIT) with high test sensitivity for cancer
• Stool DNA test (sDNA), with high sensitivity for cancer, interval uncertain

Your doctor may use any of these different tests to determine if colorectal cancer is present. For example, a fecal occult blood test can check for hidden blood in the stool. According to the U.S. Centers for Disease Control and Prevention (CDC), studies show a 33 percent drop in deaths from colorectal cancer for people who had an annual fecal occult blood test.

Flexible sigmoidoscopy uses a small lighted tube to inspect the wall of the rectum and part of the colon. (Read about "Flexible Sigmoidoscopy") The CDC says up to three quarters of polyps and 65 percent of cancers can be detected this way. For people over the age of fifty, even if they have no symptoms or known risk factors other than age, AMA recommends an annual fecal occult blood test and/or flexible sigmoidoscopy at least every five years. Higher risk individuals may need more aggressive screening; ask your doctor.

Colonoscopy, which inspects the entire colon, is also used at times. Traditional colonoscopy uses a tube with a camera and lights to inspect the colon. What is called virtual colonoscopy uses imaging techniques. (Read about "Colonoscopy") In both colonoscopy and sigmoidoscopy, the doctor can also take samples of tissues for more examination. (Read about "Biopsy") Doctors can also manually examine the area or use a series of x-rays using a double contrast barium enema to help outline the area on the x-rays. (Read about "X-rays")

If any of these tests indicates a potential problem, a colonoscopy is likely to be performed to confirm the diagnosis.

Once cancer of the colon or rectum is found, more tests will be done to find out if cancer cells have spread to other parts of the body. This is called staging. The doctor needs to know the stage of the disease to plan treatment. The following stages are used for cancer of the colon and rectum, according to NCI:

Stages of colon cancer

• Stage 0 (Carcinoma in Situ)

  In stage 0, the cancer is found in the innermost lining of the colon only. Stage 0 cancer is also called carcinoma in situ.

• Stage I

  In stage I, the cancer has spread beyond the innermost lining of the colon to the second and third layers and involves the inside wall of the colon, but it has not spread to the outer wall of the colon or outside the colon. Stage I colon cancer is sometimes called Dukes' A colon cancer.

• Stage II

  In stage II, cancer has spread outside the colon to nearby tissue, but it has not gone into the lymph nodes. (Lymph nodes are small, bean-shaped structures that are found throughout the body. They filter substances in a fluid called lymph and help fight infection and disease.) (Read about "The Lymph System") Stage II colon cancer is sometimes called Dukes' B colon cancer.

• Stage III

  In stage III, cancer has spread to nearby lymph nodes, but it has not spread to other parts of the body. Stage III colon cancer is sometimes called Dukes' C colon cancer.

• Stage IV

  In stage IV, cancer has spread to other parts of the body, such as the liver or lungs. Stage IV colon cancer is sometimes called Dukes' D colon cancer.

Stages of rectal cancer:

• Stage 0 (carcinoma in situ)

  In stage 0, cancer is found in the innermost lining of the rectum only. Stage 0 cancer is also called carcinoma in situ.

• Stage I

  In stage I, cancer has spread beyond the innermost lining of the rectum to the second and third layers and involves the inside wall of the rectum, but it has not spread to the outer wall of the rectum or outside the rectum. Stage I rectal cancer is sometimes called Dukes' A rectal cancer.

• Stage II

  In stage II, cancer has spread outside the rectum to nearby tissue, but it has not gone into the lymph nodes (small, bean-shaped structures found throughout the body that filter substances in a fluid called lymph and help fight infection and disease). (Read about "The Lymph System") Stage II rectal cancer is sometimes called Dukes' B rectal cancer.

• Stage III

  In stage III, cancer has spread to nearby lymph nodes, but it has not spread to other parts of the body. Stage III rectal cancer is sometimes called Dukes' C rectal cancer.

• Stage IV

  In stage IV, cancer has spread to other parts of the body, such as the liver, lungs or ovaries. Stage IV rectal cancer is sometimes called Dukes' D rectal cancer.

Treatment

If cancer is present, NCI says surgery to remove the tumor is the most common treatment. Different types of surgery for this cancer include:

• Colonoscopy - A small malignant polyp may be removed from your colon or upper rectum with a colonoscope. Some small tumors in the lower rectum can be removed through your anus without a colonoscope.
• Laparoscopy - Early colon cancer may be removed with the aid of a thin, lighted tube (laparoscope). Three or four tiny cuts are made into your abdomen. The surgeon sees inside your abdomen with the laparoscope. The tumor and part of the healthy colon are removed. Nearby lymph nodes also may be removed. The surgeon checks the rest of your intestine and your liver to see if the cancer has spread.
• Open surgery - The surgeon makes a large cut into your abdomen to remove the tumor and part of the healthy colon or rectum. Some nearby lymph nodes are also removed. The surgeon checks the rest of your intestine and your liver (Read about "The Liver") to see if the cancer has spread.

When a section of your colon or rectum is removed, the surgeon can usually reconnect the healthy parts. However, sometimes reconnection is not possible. In this case, NCI says the surgeon creates a new path for waste to leave your body. The surgeon makes an opening (stoma) in the wall of the abdomen, connects the upper end of the intestine to the stoma, and closes the other end. The operation to create the stoma is called a colostomy. A flat bag fits over the stoma to collect waste, and a special adhesive holds it in place. For most people, the stoma is temporary. It is needed only until the colon or rectum heals from surgery. After healing takes place, the surgeon reconnects the parts of the intestine and closes the stoma. Some people, especially those with a tumor in the lower rectum, need a permanent stoma.

In addition to surgery, chemotherapy or radiation may also be used. Biological therapy may also be an option. All treatment plans should be carefully discussed with your doctor. (Read more on these therapies in "Cancer Treatments")

As with so many other types of cancer, early detection can increase your chances of surviving colorectal cancer. Unfortunately, many people shy away from discussing this topic, even with their doctor.

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For a list of individual types of cancer, see Cancer: What It Is