Screening for CRC: Important
Colorectal cancer (CRC) is cancer that affects the lower intestine and/or the rectum. Overall, the incidence of CRC has been declining in the U.S., however it still ranks third as a cause of cancer-related death. A closer look at the statistics reveals that the incidence of CRC has been declining in persons 55 years or older, but since the mid-1990s the incidence has risen annually by 0.5 to 1.3 percent in adults aged 40 to 54. The reason for the rising rate in younger people has not been found so far, but the fact that it is rising in younger people has caused experts to rethink recommendations for screening for CRC. In May, the Journal of the American Medical Association published recently updated screening recommendations from the US Preventive Services Task Force (USPSTF). The USPSTF is a quasi-governmental group of medical experts that reviews studies and data on diseases and conditions and make recommendations on screening for them. I have written about their recommendations before.
While symptoms of CRC may include changes in bowel habits, abdominal pain, and blood in the stool, it is often asymptomatic in the early stages when it is both treatable and curable. Sometimes it is discovered by accident, for example finding unexplained iron-deficiency anemia on routine blood testing. Because it often has no symptoms early on, regular screening for CRC is very important. Screening used to include hemoccult testing (test for blood in the stool) and flexible sigmoidoscopy, however here in the U.S. those tests have been replaced by other, more reliable tests. Home tests like Cologuard look for human DNA in the stool and other similar fecal immunochemical tests are available. Unfortunately, these tests do have both false-positive and false-negative results.
For example, the Cologuard test may be positive if the individual has hemorrhoids that bleed occasionally. CT colonography, often called virtual colonoscopy, and colonoscopy are the tests of choice. Both require bowel prep, but colonoscopy is both diagnostic and therapeutic, meaning polyps and suspicious areas may be biopsied or removed at the time of the test.
Getting back to the USPSTF recommendations, they now recommend beginning screening for CRC starting at age 45, down from the previous recommendation of age 50. This recommendation applies to those who have no symptoms of CRC and who do not have a higher risk for it. Individuals at higher risk include those who have a family history of CRC, those with inflammatory bowel disease (Crohn’s disease and ulcerative colitis), and those with a history of colon polyps. The USPSTF recommendations also include softening the screening requirements for those aged 75 and up, again only if not high risk. They recommend that those aged 75 and up discuss screening with their doctor and determine the need for screening on an individual basis.
Screening for CRC can prevent people from dying from it, often at an earlier age. Some estimates are that regular screening for CRC can add as much as 22 years to one’s life expectancy. Naturally, the life benefit from screening decreases with age, which is why the recommendation changed for those aged 75 and older, as studies have shown that that age group benefits the least from screening, unless they have never been screened before. If you exclude the angst created by false positive screening results, harms from screening are mostly limited to colonoscopy, and, although rare, they include bleeding, infection, and bowel perforation.
For more information go to the USPSTF website at: www.uspreventiveservicestaskforce.org
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By Peter Galvin, MD