Screening for colorectal cancer saves lives. This message couldn’t be any clearer, says Robert Kurtz, Chief of Memorial Sloan Kettering’s Gastroenterology and Nutrition Service. “We can prevent colon cancer.”
Most types of screening, such as mammograms and skin checks, look for cancer after it’s already developed, with the goal of finding it as early as possible. Colorectal cancer screening, though, looks for precancerous signs, such as fleshy growths called polyps. By removing these growths, your doctor can actually prevent cancer from developing.
Colorectal cancer is the third most common and second most deadly cancer among adults in the United States. And while there has been an almost 30 percent reduction in deaths over the past several years, since the push for screening began, that statistic could be much better. About one-third of Americans between the ages of 50 and 75 — the group at highest risk for colorectal cancer — have not been screened, according to the Centers for Disease Control.
Preparing for Screening
Why are so many people not being screened? For one thing, colonoscopy, the most effective method for colorectal cancer screening, requires preparation. To do a colonoscopy, your doctor inserts a colonoscope, a long tube with a camera and light on one end. This tube moves through your colon and sends images back to a screen. If your doctor sees a polyp, he or she can very likely remove it right away and send it to the lab for testing. Most people who have a colonoscopy receive an anesthetic and don’t remember the procedure at all.
However, prepping for a colonoscopy isn’t comfortable for some people, Dr. Kurtz explains. It involves having to take strong laxatives to completely clean out your colon. This is important so your doctor can see the colon walls and any suspicious spots.
MSK recommends colonoscopy once every ten years for people age 50 and older who are at average risk for colorectal cancer. Those at higher risk because of family history or other factors may need to have them more frequently and before age 50. Learn more about our screening recommendations for colorectal cancer.
“If the patient hasn’t done an adequate job of preparing the colon, we’re going to be missing things,” Dr. Kurtz adds. “You can’t really see anything or see small polyps if there’s a lot of residual stool left behind.”Back to top
Other Screening Methods
For some, a virtual colonoscopy is a better choice for screening than standard colonoscopy. It still requires the same preparation, but it uses CT images to see the colon walls instead of a colonoscope and no anesthetic is needed. A small tube is inserted into the rectum during the procedure in order to push air into the colon, making it bigger and easier to visualize using the CT scanner.
Virtual colonoscopies are good for detecting suspicious spots, says Dr. Kurtz. But if any polyps are found, you still need to have a regular colonoscopy to have them removed. This means having to do the prep twice if the second colonoscopy can’t be done right away.
While there are no other exams as effective at finding colorectal cancer or polyps as colonoscopy, there are two other types of tests that may help detect signs of cancer: the fecal occult blood test and the stool DNA test. Both check for blood in the stool; the DNA test also looks for DNA mutations that could mean there is something going on inside the colon. Both tests can only tell if something suspicious is showing, however. If they’re positive, you still need a colonoscopy to find out exactly what the tests found.
“The DNA test is coming along. There are some good papers that suggest that it’s very worthwhile,” Dr. Kurtz says.
The bottom line, says Dr. Kurtz, is that patients need to speak with their doctors about screening, no matter which type of test they choose. “Screening really can save your life.”Back to top