How many illnesses allow you to say that one screening test can prevent a death?
In the case of colorectal cancer, the second-leading cancer killer in the U.S., a colonoscopy can prevent six of every 10 deaths. Imagine not just detecting cancer but preventing it.
How is that possible?
Colorectal cancer usually starts from polyps in the colon or rectum. A polyp is a growth that shouldn’t be there, and can turn into cancer. Screening tests such as colonoscopies can find polyps so they can be removed before they turn into cancer.
Other screening tests can find colorectal cancer early, when the chance of being cured is high. In fact, if everyone 50 or older had regular screening tests, at least 60 percent of deaths from this cancer could be avoided.
When colorectal cancer is found at an early stage before it has spread, the five-year relative survival rate is about 90 percent. But only about four of 10 colorectal cancers are detected early, the American Cancer Society reports. When cancer has spread outside the colon or rectum, survival rates are lower.
The gold standard in screening is the colonoscopy. Other, somewhat less invasive screenings exist, but typically, suspicious findings from these screenings end up requiring a follow-up colonoscopy anyway.
These screening tests can find polyps and cancer:
- Colonoscopy: A doctor uses a flexible, lighted tube with a small camera on the end to view the entire colon and rectum. If polyps are found, they can be removed during the colonoscopy. Typically, patients are asked to follow a special diet for a day or two before the test and clean out their colons with strong laxatives (a bowel prep). Most people are sedated during the test, so you’ll need a driver to accompany you. If your test shows no abnormalities, you won’t need another for 10 years.
- Flexible sigmoidoscopy: Similar to a colonoscopy, this test looks at only part of the colon and rectum. Any polyps found can be removed during the test, but a colonoscopy will be needed to see the rest of the colon. Most people are not sedated for this test. Flexible sigmoidoscopy must be repeated every five years.
- Double-contrast barium enema: Because the gut does not show up well on X-rays, this test involves putting a liquid containing barium into the rectum. The liquid spreads through the colon, air is pumped in, and X-rays are taken. This requires a bowel prep but no sedation. If polyps or suspicious areas are found, a follow-up colonoscopy is necessary. This test must be repeated every five years.
- CT colonography: Also called virtual colonoscopy, this scan of the colon and rectum produces detailed cross-sectional images that a doctor views for polyps or cancer. Air is pumped into the rectum and colon, and a CT scanner takes images of the colon. It requires bowel prep but no sedation. If a doctor spies something that needs to be biopsied, a follow-up colonoscopy is needed. This test must be done every five years.
Tests that mainly find cancer:
- Guaiac-based fecal occult blood test (gFOBT) and fecal immunochemical test (FIT): These tests can find blood in the stool that could be a sign of cancer or large polyps. These are take-at-home tests using a kit from a doctor’s office. A positive result must be followed up with a colonoscopy. Many times, the cause of blood is something non-cancerous, such as ulcers or hemorrhoids. These tests need to be done every year.
Discuss with your doctor which test is right for you. If you are over 50, get tested. Colon cancer occurs most often in people over 50, and the risk increases with age. Colon cancer can be prevented. Treatments have improved so much over the decades that today America is home to more than 1 million colorectal cancer survivors, the American Cancer Society says.