September 19, 2013
News Review From Harvard Medical School -- Studies: Colon Cancer Screening Saves Lives
Screening tests for colon cancer reduce deaths by one-third to one-half, 2 new studies find. The first study included nearly 89,000 health professionals. Researchers kept track of them for about 22 years. People who had a screening colonoscopy that found no problems were 56% less likely to die of colon cancer than those who had no screening tests. Colon cancer deaths were 40% lower for people who had a screening sigmoidoscopy that found no problems. Both tests look at the inside of the colon. A colonoscopy looks at the whole colon. A sigmoidoscopy looks at only the lower portion. A second study randomly divided 46,500 older adults into 3 groups. Two groups received fecal occult blood tests. This test looks for blood in the stool, which can indicate possible colon cancer. The third group received "usual care." Few people in this group got the test. Compared with the usual-care group, colon cancer deaths were reduced 32% for the group that got annual fecal occult blood tests and 22% lower in the group that got tests every 2 years. The New England Journal of Medicine published the studies. HealthDay News wrote about them September 18.
By Robert H. Shmerling, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
Screening for cancer may seem like a simple process: Perform a test, find cancer early and cure it.
Yet it's not so simple. For many types of cancer:
Perhaps this explains why we have good screening tests for only a few types of cancer. These include cancers of the colon, breast and cervix.
For colon cancer, we have several screening tests. They include:
But there is uncertainty regarding just how much benefit these tests provide. Two new studies address these questions. They appear in the current issue of the New England Journal of Medicine.
In the first study, researchers kept track of nearly 89,000 adults for 22 years. Some had colonoscopy or sigmoidoscopy. Others had no screening. About 2% of the total group developed colon cancer, and 0.5% died of the disease.
In the other study, more than 46,000 adults were randomly divided into 3 groups. Two of the groups received stool testing -- every year or every 2 years. A comparison group received "usual care," with a low rate of stool testing. Screening occurred during two 6-year periods. Up to 30 years later, about 2% of the total group had died of colon cancer.
These studies concluded that:
Taken together, these findings support current advice for adults to have a screening colonoscopy beginning at age 50. Sigmoidoscopy may be a worthwhile alternative, though its benefit was less. Doctors may recommend stool testing, too. But the ideal combination of tests has not been well studied.
People with average risk of colon cancer are advised to get a repeat colonoscopy every 10 years. These findings suggest that this may be more frequent than necessary.
Health care professionals and public health officials can use studies like these to encourage colon cancer screening.
What Changes Can I Make Now?
Do what you can to prevent colon cancer.
There is some evidence that taking a daily aspirin or folic acid may reduce the risk of colon cancer. However, this is not proven. Review these options with your doctor as well.
What Can I Expect Looking to the Future?
We are likely to have better cancer screening tests in the future. However, a lot of research will be needed to prove their worth. A good example is lung cancer. Recent research suggests that CT scans may help to detect lung cancer in people at high risk.
Currently, the biggest challenge for colon cancer screening is getting people to get the available tests. You can expect to hear public health campaigns encouraging screening. About 50,000 Americans die of colon cancer each year. This new research confirms that many of those deaths are preventable. So I am hopeful that screening will become more widespread.