Colorectal Cancer
Colorectal cancer is a term used to refer to cancer that starts in the colon or rectum. Colon and rectal cancers begin in the digestive system, also called the GI (gastrointestinal) system. Over 95% of colon and rectal cancers are adenocarcinomas. These are cancers of the cells that line the inside of the colon and rectum.
Risk Factors for Colorectal Cancer
Age: Age 50 or higher increases the risk of colorectal cancer. More than 9 out of 10 people found to have colorectal cancer are older than 50.
Previous colorectal cancer: Even if a colorectal cancer has been completely removed, you are more likely to have new cancers start in other areas of your colon and rectum. The chances of this happening are greater if you had your first colorectal cancer when you were age 60 or younger.
History of polyps: Some types of polyps increase the risk of colorectal cancer, especially if they are large or if there are many of them.
History of bowel disease: Two diseases, called ulcerative colitis and Crohn’s disease, increase the risk of colon cancer. In these diseases, the colon is inflamed over a long period of time. If you have either of these diseases your doctor may want you to have colon screening testing more often.
Family history: If you have close relatives who have had this cancer, your risk is increased. This is especially true if the family member got the cancer before age 60. People with a family history of colorectal cancer should talk to their doctors about how often to have screening tests.
Family syndromes: A syndrome is a group of symptoms. For example, in some families, members tend to get a type of syndrome that involves having hundreds of polyps in their colon or rectum. Cancer often develops in one or more of these polyps.
If your doctor tells you that you have a condition that makes you or your family members more likely to get colorectal cancer, you will probably need to begin colon cancer testing at a younger age and you might think about genetic counseling.
Ethnic background: Some studies have found that Jews of Eastern European descent (Ashkenazi Jews) have the highest colorectal cancer risk of any ethnic group in the world. Several kinds of gene changes (mutations) account for some, but not all, of this increased risk.
Race: African Americans have the highest number of colorectal cancer cases and the highest death rates from colorectal cancer of all racial groups in the United States. The reason for this is not yet known.
Diet: A diet high in fat, especially fat from animal sources, can increase the risk of colorectal cancer. Over time, eating a lot of red meats and processed meats can increase colorectal cancer risk.
Lack of exercise: People who are not active have a higher risk of colorectal cancer.
Overweight: Being very overweight increases a person's risk of dying from colorectal cancer.
Smoking: Most people know that smoking causes lung cancer, but recent studies show that smokers are 30% to 40% more likely than nonsmokers to die of colorectal cancer. Smoking increases the risk of many other cancers, too.
Alcohol: Heavy use of alcohol has been linked to colorectal cancer.
Diabetes: People with diabetes have a 30% increased chance of getting colorectal cancer. They also tend to have a higher death rate from this cancer.
Factors that Are Less Certain
Night-shift work: One study suggests that working a night shift at least 3 nights a month for at least 15 years might increase the risk of colorectal cancer in women. More research is needed to check out this finding.
Other cancers and their treatment: A recent report on testicular cancer survivors found that these men had a higher rate of colorectal cancer. Men who receive radiation therapy for prostate cancer have been reported to have a higher risk of rectal cancer, too.
Prevention:
People who have a history of colorectal cancer in their family should check with their doctor for advice about screening tests or other tests to find cancer early.
Diet and exercise: People can lower their risk of getting colorectal cancer by taking charge of the risk factors that they can control, such as diet and exercise. It is important to eat plenty of fruits, vegetables, and whole grain foods and to limit intake of high-fat foods. Getting enough exercise is also important. The American Cancer Society recommends at least 30 minutes of physical activity on 5 or more days of the week. Forty-five to 60 minutes of exercise on 5 or more days of the week is even better.
Vitamins: Some studies suggest that taking a daily multivitamin containing folic acid or folate can lower colorectal cancer risk. Other studies suggest that getting more calcium and vitamin D can help. One recent study suggested that a diet high in magnesium may also reduce colorectal cancer risk in women.
Female hormones: Hormone replacement therapy (HRT) in women after menopause may reduce their risk of getting colorectal cancer. But those women on HRT who do get colorectal cancer may have a fast growing cancer. The decision to use HRT should be based on a careful discussion of benefits and risks with your doctor.
Other factors: People with a family history of colorectal cancer may benefit from starting screening tests when they are younger and having them done more often than people without this risk factor. Genetic tests can also help tell which members of certain families have inherited a high risk for getting colorectal cancer. The results of genetic tests can help people make screening and treatment decisions.
Early Detection:
There are several tests used to look for colorectal cancer.
Stool blood test (fecal occult blood test or FOBT): This test is used to find small amounts of hidden (occult) blood in the stool. Very small amounts of blood can be in the stool when polyps or cancers start to form. A sample of stool is tested for any traces of blood. People having this test will receive a kit that explains how to take stool samples at home. The kit is then sent to a lab for testing. If the results are positive, further tests, such as a colonoscopy, will be done to find the exact cause of the bleeding.
A newer kind of stool blood test is known as FIT (fecal immunochemical test). It is very much like the FOBT but gives a fewer number of false results. Just like the FOBT, if the results are positive, further tests, such as a colonoscopy, will be done to find the exact cause of the bleeding.
Flexible sigmoidoscopy: A sigmoidoscope is a slender, lighted tube about the thickness of a finger. It is placed into the lower part of the colon through the rectum. This allows the doctor to look at the inside of the rectum and part of the colon for cancer or polyps. Because the tube is only about 2 feet long, the doctor is only able to see about half of the colon. The test can be uncomfortable, but it should not be painful. Before the test, you will need to take an enema to clean out the lower colon. If a small polyp is found your doctor may remove it during this test. If an adenoma polyp or colorectal cancer is found during the flex-sig, you will need to have a colonoscopy to look for polyps or cancer in the rest of the colon.
Colonoscopy: A colonoscope allows the doctor to see the entire colon. If a polyp is found, the doctor may remove it. If anything else looks abnormal, a biopsy might be done. To do this, a small piece of tissue is taken out through the colonoscope. The tissue is sent to the lab to see if cancer cells are present. This test can be uncomfortable. To avoid this, you will be given medicine through a vein to make you feel relaxed and sleepy.
Barium enema with air contrast: To do this test a chalky substance is used to partly fill and open up the colon. Air is then pumped in to cause the colon to expand. This allows good x-ray pictures to be taken. If an area does not look normal you will need to have a colonoscopy.
Virtual colonoscopy: You might think of this as a super x-ray of the colon. Air is pumped into the colon to cause it to expand, and then a special CT scan is done. Right now, this test is not among those recommended by the ACS or other major medical organizations for finding colon cancer early. More studies are needed to find out if it is as good as or better than other tests used to find colon cancer early.
American Cancer Society Colorectal Cancer Screening Guidelines
Beginning at age 50, both men and women at average risk should have 1 of the 5 of the screening options:
- yearly stool blood test (FOBT) or fecal immunochemical test (FIT), or
- flexible sigmoidoscopy every 5 years, or
- yearly stool blood test plus flexible sigmoidoscopy every 5 years (Of these first 3 options, the ACS prefers the third option, that is, FOBT or FIT every year plus flexible sigmoidoscopy every 5 years.)
- Or you may have: double contrast barium enema every 5 years, or
- colonoscopy every 10 years
Treatment:
The 4 main types of treatment for colorectal cancer are surgery, radiation therapy, chemotherapy (often called just "chemo"), and newer, targeted therapies (called monoclonal antibodies). Depending on the stage of your cancer, 2 or more types of treatment may be used at the same time, or used one after the other.
Treatment Centers in Georgia:
Support Groups:
Colorectal Cancer
- Saint Joseph’s Hospital, Atlanta. Cancer Center Conference Room, 1st Friday, 10:00 am. Contact: Renee Rickles (404) 851-5051
- Winship Cancer Institute, Atlanta. Room C1166B, 2nd Wednesday, 3:00 p.m. Contact: Rebecca Sizemore (404) 778-5926
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