Risk factors

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This image of the inside of the colon shows two small polyps whose diameters are about the size of a pencil eraser (about 6 to 7 millimeters). This image of the inside of the colon shows a large polyp. Large polyps are 10 millimeters (mm) or larger in diameter (25 mm equals about 1 inch). This image of the inside of the colon shows colon cancer. More On This Topic Colon polyps Risk factors Colon and rectal cancers can occur at any age, and no one is too young to develop colorectal cancer. However, about 90 percent of people with the disease are older than 50. Factors other than age that place you at a higher risk include: Inflammatory intestinal conditions. Long-standing inflammatory diseases of the colon, such as ulcerative colitis and Crohn's disease, can increase your risk. Family history. You're more likely to develop colorectal cancer if you have a parent, sibling or child with the disease. If many family members have colon cancer or rectal cancer, your risk is even greater. In some cases, this connection may not be hereditary or genetic. Instead, cancers within the same family may result from shared exposure to an environmental carcinogen or from diet or lifestyle factors. Familial adenomatous polyposis (FAP) is a rare hereditary disorder that causes you to develop hundreds of polyps in the lining of your colon and rectum. If these go untreated, you'll likely develop colon cancer by age 40. In most cases, genetic testing can help determine if you're at risk of FAP. FAP may also cause noncancerous tumors to develop in other parts of your body, including your skin (sebaceous cysts and lipomas), bone (osteomas) and abdomen (desmoid tumors). Hereditary nonpolyposis colorectal cancer (HNPCC) is another hereditary disorder that can put you at high risk of developing colon cancer or rectal cancer at an early age. Unlike FAP, however, you may have relatively few polyps. If you're Jewish and of Eastern European descent, you may have an inherited tendency to develop colon cancer or rectal cancer. This is particularly true of Ashkenazi Jews. Diet. Colon cancer and rectal cancer may be associated with a diet low in fiber and high in fat and calories. Research is still occurring in this area. However, high-fiber, low-fat diets have additional health benefits apart from a potential connection to colorectal cancer prevention. A sedentary lifestyle. If you're inactive, you're more likely to develop colorectal cancer. This may be because when you're inactive, waste stays in your colon longer. Getting regular physical activity may reduce your risk. Diabetes. People with diabetes have up to a 40 percent increased risk of developing colorectal cancer. Smoking. More than one in 10 fatal colon cancers may be caused by smoking. Once diagnosed with colorectal cancer, smokers face a 30 percent to 40 percent increased risk of dying of the disease. Alcohol. Heavy use of alcohol may increase your odds of colorectal cancer. A personal history of colorectal cancer or polyps. If you've already had colorectal cancer or adenomatous polyps, you have a greater risk of colorectal cancer in the future. More On This Topic Genetic testing for colon and rectal cancer Alcohol and your health: Weighing the pros and cons When to seek medical advice If you notice any symptoms of colon cancer, such as blood in your stool or a persistent change in bowel habits, see your doctor as soon as possible. Keep in mind that colorectal cancer can strike younger as well as older people. If you're at high risk, don't wait until symptoms appear. See your doctor for regular screenings. The American Cancer Society recommends colorectal screenings beginning at age 50 and more frequent or earlier screening if you have other risk factors, such as a family history of the disease. Medicare has expanded its coverage of screening procedures. If you're older than 50 and have Medicare benefits, Medicare will cover annual fecal occult blood tests and sigmoidoscopy every four years. If you're at high risk of colorectal cancer, you'll be covered for colonoscopy every two years, or every 10 years if you're of average risk. Double contrast barium enema — which is sometimes supplemented with flexible sigmoidoscopy — can be used as an alternative, if your doctor thinks it's a better choice for you. Screening and diagnosis Most colon cancers develop from adenomatous polyps. Screening is extremely important for detecting polyps before they become cancerous. It can also help find colorectal cancer in its early stages when you have a good chance for recovery. Like many people, you may be embarrassed by the screening procedures, worried about discomfort or afraid of the results. Try not to let these concerns stand in your way. Most procedures are only moderately uncomfortable, and working with a doctor you like and trust should help ease your embarrassment. Common screening and diagnostic procedures include the following: Digital rectal exam. In this office exam, your doctor uses a gloved finger to check the first few inches of your rectum for large polyps and cancers. Although safe and painless, the exam is limited to your lower rectum and can't detect problems with your upper rectum and colon. In addition, it's difficult for your doctor to feel small polyps. Fecal occult (hidden) blood test. This test checks a sample of your stool for blood. It can be performed in your doctor's office, but you're usually given a kit that explains how to take the sample at home. You then return the sample to a lab or your doctor's office to be checked. The problem is that not all cancers bleed, and those that do often bleed intermittently. Furthermore, most polyps don't bleed. This can result in a negative test result, even though you may have cancer. On the other hand, if blood shows up in your stool, it may be the result of hemorrhoids or an intestinal condition other than cancer. For these reasons, many doctors recommend other screening methods instead of, or in addition to, fecal occult blood tests. Flexible sigmoidoscopy. In this test, your doctor uses a flexible, slender and lighted tube to examine your rectum and sigmoid — approximately the last 2 feet of your colon. The test usually takes just a few minutes. It can sometimes be uncomfortable, and there's a slight risk of perforating the colon wall. If a polyp or colon cancer is found during this exam, your doctor will recommend colonoscopy to look at the entire colon and remove any polyps that are present for examination under a microscope. Barium enema. This diagnostic test allows your doctor to evaluate your entire large intestine with an X-ray. Barium, a contrast dye, is placed into your bowel in an enema form. During a double contrast barium enema, air is also added. The barium fills and coats the lining of the bowel, creating a clear silhouette of your rectum, colon and sometimes a small portion of your small intestine. There's also a slight risk of perforating the colon wall and the test has a significantly high rate of missing important lesions. A flexible sigmoidoscopy is often done in addition to the barium enema to aid in detecting small polyps that a barium enema X-ray may miss, especially in the lower bowel and rectum. Colonoscopy. This procedure is the most sensitive test for colon cancer, rectal cancer and polyps. Colonoscopy is similar to flexible sigmoidoscopy, but the instrument used — a colonoscope, which is a long, flexible and slender tube attached to a video camera and monitor — allows your doctor to view your entire colon and rectum. If any polyps are found during the exam, your doctor may remove them immediately or take tissue samples (biopsies) for analysis. This is done through the colonoscope and is painless. If you have adenomatous polyps, especially those larger than 5 millimeters in diameter, you'll need careful screening in the future.