In May 2018, the American Cancer Society (ACS) lowered its recommended starting age for colorectal cancer (CRC) screening from 50 to 45, in response to rising rates of this cancer in younger people. That would cover an extra 22 million Americans. Guidelines from nearly all expert groups, including the influential U.S. Preventive Services Task Force (USPSTF), the CDC, and the VA, recommend starting CRC screening at age 50 and continuing to age 75, based largely on the same data that the ACS evaluated.
Most media reports presented the ACS change as a good thing, but some experts have criticized the change as being premature, at best. Here’s what I think.
Many of the news reports glossed over the fact that this ACS recommendation is “qualified,” meaning there’s “less certainty” about the “balance of benefits and harms,” unlike its strong recommendation for screening those 50 and older. There is no evidence from clinical trials that routinely screening younger people will have the same benefits as screening older folks.
The ACS didn’t base its advice on new clinical data, but on a new “modeling study” of the benefits and risks, which is open to question. Despite rising rates of CRC (rectal cancer, in particular) in Americans under 50, the numbers are still relatively small, especially compared to older people.
What’s more, during the past 30 years, CRC death rates have not risen in younger people, which is reassuring. Meanwhile, death rates have dropped dramatically in older people and would be falling even more if everyone ages 50 to 75 were screened as recommended (one-third have not been screened).
What could be the risks of early screening? The lower CRC rate in people under 50 increases the odds that abnormal findings from screening tests will be false-positive results rather than potentially life-threatening lesions. Such false alarms may be quickly ruled out by follow-up tests, but may be misdiagnosed and lead to yet more testing, anxiety, and possibly unnecessary treatment. In addition, screening millions of lower-risk younger adults may be a costly use of health-care resources.
This is a good opportunity to refocus attention on CRC screening, which can not only detect cancer early, when it is often curable, but also prevent it by leading to the removal of polyps (adenomas) that can become malignant. There are several screening options, notably colonoscopy every 10 years, sigmoidoscopy every five years, or annual stool tests (preferably a fecal immunochemical test, or FIT). The ACS and USPSTF advise that the decision to test people ages 76 to 85 years should be individualized, taking into account their overall health and screening history—and that people over 85 should stop getting screened.
If you are 45 to 49 years old and want to consider early CRC screening, discuss it with your doctor, keeping in mind that data about its advisability are limited, the benefits-to-harms ratio may not be as favorable as it is for older people, and insurance may not cover it. African Americans, in particular, may wish to start screening at age 45, since they are at higher risk for CRC than white Americans.
The ACS recommends starting screening even earlier if you have inflammatory bowel disease (such as ulcerative colitis or Crohn’s disease) or a family history of CRC, of certain types of polyps, or of a hereditary CRC syndrome such as Lynch syndrome.
Whatever your age, if you are experiencing symptoms that may indicate colorectal cancer, seek medical attention. These include a change in bowel habits that lasts more than a few days, bloody or black stool, rectal bleeding, abdominal pain, unexplained weakness and fatigue, and unintentional weight loss. Don’t just assume that bloody stool is caused by hemorrhoids.
For more about CRC screening, see Do You Need a Colonoscopy?
This article first appeared in the UC Berkeley Wellness Letter.