Division of Gastroenterology & Hepatology
Colorectal Cancer Screening
The colon, or the large intestine, is at the end of the digestive system. Its primary function is to desiccate (dry), package, and store the waste left over after food is digested and absorbed by the small intestine. The colon very efficiently absorbs water and reduces the volume of waste that needs to be eliminated in the stool in a convenient form at a convenient time.
Cancer of the colon and rectum – called colorectal cancer (CRC) is the second leading cause of cancer deaths among men and women in the United States. However, if detected early, colorectal cancer can be cured. With simple preventive steps, you can greatly reduce your risk of developing the disease. It is important for you to understand -your risks for colorectal cancer, the symptoms, and screening tests that can detect cancerous growths.
Colorectal cancer develops from non-cancer polyps. A polyp is a grape-like growth on the inside wall of the colon or rectum. Polyps grow slowly over three to ten years. Most people do not develop polyps until after the age of 50. Some polyps become cancerous, others do not. In order to prevent colorectal cancer, it is important to get screened to find out if you have polyps, and to have them removed if you do. Removal of polyps has been shown to prevent colorectal cancer.
How Do I Know if I´m at Risk for Colorectal Cancer?
Everyone has a risk of developing CRC. However, your risk depends on several factors.
You are at average risk for colorectal cancer if you are:
50 years or older and have no other risk factors
You are at increased risk for colorectal cancer if you:
Have a personal history of CRC or adenomatous polyps.
Have a family history – one or more parents, brothers and/or sisters or children – of CRC or adenomatous polyps.
Have a family history of multiple cancers, involving the breast, ovary, uterus, and other organs.
Have a personal history of inflammatory bowel disease, such as ulcerative colitis or Crohn's Disease.
There are several inherited disorders that greatly increase your risk of CRC. However, they are not very common.
Other factors that increase your risk of developing CRC are:
A diet that is low in fiber and high in fat.
Aren't Women at Less Risk for Colorectal Cancer than Men?
Men and women are equally affected by colorectal cancer. In fact, colorectal cancer is the third leading cause of cancer death in women. Also, about 67,000 women are diagnosed with this cancer each year and more than 40% of them – 28,600 – die from the disease.
What are the Symptoms of Colorectal Cancer?
Colorectal cancer begins with no symptoms at all. However, over time, there are a number of warning signs:
Blood in your stool (bright red, black, or very dark)
A change in your bowel movements, especially in the shape of the stool (e.g. narrow like a pencil)
Cramping pain in your lower abdomen
Frequent gas pain
Discomfort in or the urge to move your bowels
What Should I Do if I have These Symptoms?
Call your doctor and schedule an appointment. Only your physician can determine if your symptoms are due to CRC.
Why is Screening Important if I Have No Symptoms?
Screening is important for two reasons. The early stage of CRC – which is when it is most curable – frequently does not cause any symptoms. And, just as important, screening is the only way to find polyps. If the polyp is removed, it cannot develop into cancer.
What Type of Screening Tests are Available?
There are several types of screening tests. Talk with your doctor about which one is best for you. People at average risk should start screening at age 50. People at increased risk start at age 40 or sooner.
Digital rectal examinations: In this test, the doctor manually inserts a gloved finger into the rectum to feel for abnormalities. While this test is easy to do, it is not very sensitive.
Fecal occult blood test (FOBT): In this procedure, the stool is tested for the presence of blood that is invisible to the eye. The test is available in a kit and can be taken at home to collect stool samples. The stool cards can be mailed to your doctor. This test is relatively easy and inexpensive, however, many factors can interfere with its accuracy. This test is recommended annually for persons beginning at age 50 for people at average risk but is also not very sensitive.
Sigmoidoscopy: Your doctor will use a long flexible, lighted tube to check the rectum and the lower part of the colon for polyps and cancer. If a polyp is found, it can be sampled through the scope and sent to a lab to be tested. This test can be performed in a doctor's office, and does not require any anesthesia or sedation, but does require limited preparation such as an enema. Insertion of the tube may be somewhat uncomfortable, and some cramping may occur during the procedure, which takes about ten minutes. After the test, there may be mild abdominal gas pains. If the doctor took a biopsy, some traces of blood may be in the stool for a few days. This test is recommended every five years beginning at age 50 for people at average risk.
Colonoscopy: This procedure is done by a gastroenterologist. He or she will use a long, flexible, lighted tube – called the colonoscope – to view the entire colon and rectum for polyps or cancer. A bowel cleansing preparation of the colon is required before the procedure. The colonoscope has a camera at the end, which can project images on a TV screen. If a polyp* is found, it can be removed by a wire loop that is passed through the colonoscope and is hooked around the base of the polyp. The doctor sends an electric current through the loop, which severs the polyp from the colon wall and pulls it out of the colon. The poly[ is then sent to a laboratory to be tested to determine if it is cancerous. This procedure requires patients to be sedated, and usually takes about 20-60 minutes. There is some pressure that can be felt from the instrument's movements and some cramping afterwards, but this is usually all that occurs. Some traces of blood may be in the stool for several days after the procedure if a biopsy was taken..
Barium enema: This test is an X-ray examination of the entire colon and rectum and may be done instead of a colonoscopy. After cleansing of the colon, a soft, flexible tube is inserted into the rectum and a liquid called barium is inserted into the tube. Special X-rays follow the flow of the barium in the colon and outline any lumps, polyps or abnormalities. A person may feel some cramping and a strong urge to defecate during the test. This procedure is recommended as a substitute for colonoscopy at ten or more year intervals.
How Do I Prepare for These Screening Tests?
Proper preparation is the most important thing you can do to help ensure you get the most accurate screening possible. Your doctor will give you complete instructions on what to do. Before any test, let your doctor know about any medicines you are taking because they may affect the test results.
What if I Am Diagnosed with Colorectal Cancer?
If you are diagnosed with CRC, surgery is generally required to remove the cancerous polyps and other malignant tissue. The type of surgery and follow-up treatment will depend on how far advanced the cancer is. In the past, a colostomy was usually necessary. However, new surgical technologies can eliminate the need for a colostomy in many patients.
How Can Colorectal Cancer be Prevented?
There is no way to completely eliminate the risk of developing CRC. That is why screening is so important. However, there is evidence that you can reduce your chance of getting CRC by doing the following:
Avoid food that are high in fat, particularly saturated fat.
Eat foods that are high in calcium
Researchers are also investigating the possibility that some drugs such as aspirin, ibuprofen, calcium supplements, folic acid and others may help prevent colorectal cancer.