Risk, Prevention and Screening
Colon cancer is the third most common cancer in the U.S. with more than 140,000 people diagnosed each year. The good news for this particular type of cancer is that it can be prevented. Seventy-five percent of cases could be avoided by risks you can control.
Estimate your risk for colon cancer.
Not getting screened: Having regular screening for colon cancer is the single best way to protect yourself. You can catch cancer earlier when it’s most treatable or prevent it from happening in the first place. See colorectal cancer screening options below. Being overweight: Always try to keep weight within a healthy range. Being overweight can increase our risk for many cancers, including colorectal cancer. Diet high in red and processed meat: Limit red meat, such as steak, hamburger and pork; and processed meat, such as bacon, sausage and bologna, to less than three servings a week. Low Physical Activity: Do something active you enjoy for at least 30 minutes a day to lower your risk of colon cancer. Activity also helps keep your weight down. Too much alcohol: If you drink, keep it to one drink or less a day. Even moderate amounts increase the risk of colon cancer. Smoking: On top of raising our risk of heart disease, stroke and emphysema, smoking is a major cause of at least 14 different cancers, including colon cancer. If you smoke, quit. Being low in certain nutrients:
- Low calcium and vitamin D: There is good evidence that adequate calcium and vitamin D protect against colon cancer. Shoot for about 1,200 mg a day of calcium and 1,000 IU a day of vitamin D.
- Lack of folate: A daily multivitamin with folate is good for nutrition and can also protect against colon cancer. One a day is all you need.
Not being on an aspirin regimen: We know one low-dose aspirin a day can lower the risk of a heart attack and long-term use can lower the risk of colon cancer. But aspirin has risks so check with your doctor first. Like all healthful behaviors, the earlier in life you start them and stick with them, the better for your long-term health.
Risks We Can’t Change
Age: Our risk for colon cancer goes up as we age, especially after 60. Being tall: Colon cancer risk is higher in women 5 feet, 8 inches or taller, and for men 5 feet, 11 inches and taller. Inflammatory bowel disease: People with inflammatory bowel disease have five times the risk of developing colon cancer, so cancer screenings are especially important. Family History: Up to 5-6 percent of colorectal cancers are caused by inherited colon cancer syndromes. You need to know your family medical history because a strong family history of colon cancer or cancer-related conditions can change recommendations for colon screening and preventive measures you may take.
Colon Cancer Screening Tests and Intervals
There are several different colorectal cancer screening tests that are used for detecting colon cancer. They should be done at the recommended intervals. It’s important to note that 75 percent of patients with colon cancer have no symptoms, and 75 percent of patients with colorectal cancer have no family history. This means starting colon cancer screening at age 50 is very important (some guidelines recommend starting at age 45).
Tests that primarily find cancer:
Fecal occult blood test (FOBT): You take multiple samples of a bowel movement at home and send them to a lab where they are tested for hidden blood, which could indicate cancer. It can be positive if you eat red meat. This should be done every year, and if it is positive, you need a colonoscopy. Fecal immunochemical test (FIT, or iFOBT): This also involves multiple samples of stool to test for blood in the stool, but this one uses antibodies to detect human hemoglobin specifically. This test is typically covered every three years. DNA Stool test: This new test, not yet available for routine screening, uses multiple samples of feces to check DNA in stool cells for genetic changes that may be a sign of colorectal cancer. It would also require a colonoscopy for a positive result.
Tests that find polyps and cancer:
Flexible sigmoidoscopy: This exam is similar to a colonoscopy in that it uses a small flexible tube to examine only the lower part of the colon without sedation and should be done every five years. If it is positive for colon polyps or cancer, you need a colonoscopy. Virtual colonoscopy: This is a type of CT scan that creates a 3D image of the inside of the colon. During the test, a small tube is inserted into the rectum to gently inflate the colon with air and scan it without sedation. This should be done every five years. Because it doesn’t involve having instruments in the colon, polyps or suspicious areas cannot be removed. You still need a colonoscopy. Barium enema: This is an X-ray of the colon taken after barium liquid is put into the rectum and colon to check for polyps and abnormal anatomy of the colon and rectum. It can also detect issues such as diverticulitis, diverticulosis, abnormal colon movement or narrowing or dilation of the colon. If any abnormalities are found, you still need a colonoscopy. In large part, barium enemas have been replaced by virtual colonoscopy. Colonoscopy: A small flexible tube with a camera at the end is used to examine the full length of the inside of the colon while you are asleep. If the exam finds polyps or other precancerous lesions, they can be removed during the test, preventing cancer from forming. Because it can take a long time for a polyp to grow into cancer, a screening colonoscopy only needs to be done every 10 years in people over 45 with normal risk. People with a strong family history of colorectal cancer or a genetic predisposition should be screened more often than every 10 years, and screening may start earlier. In patients over age 50, doctors find colon polyps 30 to 40 percent of the time. But the polyps they find have been changing. Twenty years ago, most colon cancers were on the left side of the colon, the descending side that ends at the anus. Now, 50 percent of cancers and polyps are being found on the right, or ascending side. The right-side polyps tend to be very flat and blend in with their background. If they are missed, they can result in cancer. The new type of polyp recently found to be precancerous is the sessile serrated adenoma (SSA), which is primarily on the right side and difficult to identify during routine colonoscopy. Gastroenterologists at Siteman have encouraged more thorough examination of the right side of the colon. Gastroenterologists are working with new equipment and techniques to greatly up the adenoma detection rate and make sure they meet or exceed national averages. High quality colonoscopy can visualize small polyps that before might have been missed. The tests that are designed to find both early cancer and polyps are preferred because you can actually prevent the cancer from forming. Only colonoscopy can actually remove the polyp or biopsy a suspicious area. Talk to your doctor about which test is best for you.
Guidelines for Determining Risk for Colorectal Cancer
You may be at high risk if you have:
- Family history of colorectal cancer, especially in a parent, sibling or child.
- Familial adenomatous polyposis (FAP).
- Hereditary non-polyposis colon cancer syndrome (HNPCC).
Your risk is also higher if you have a personal history of:
- Polyps in the colon or rectum.
- Inflammatory bowel disease or Crohn’s disease.
Consider having a Hereditary Cancer Risk Assessment if:
- You have a family history of cancer and want to learn more specifics about that risk.
- Have a family member with inherited cancer, FAP or HNPCC.
- Have thought about taking medication or having surgery because of that risk.
Symptoms to Watch For
- Blood (either bright red or very dark) in bowel movements.
- Changes in bowel habits, such as frequent diarrhea or constipation.
- Frequent gas pains, swelling or cramps.
- Stools that are narrower than usual.
- Losing weight without trying.
- Feeling very tired.