Kevin Lomangino is the managing editor of HealthNewsReview.org. He tweets as @KLomangino.
The American Cancer Society (ACS) has updated its colorectal cancer screening guidelines, lowering the recommended age to start screening from 50 to 45.
Many national outlets picked up the potentially practice-changing news with these headlines:
Why is the ACS recommending that people get screened at a younger age?
The rate of colon cancer in younger people is rising, according to the stories, all of which featured some version of this quote from NBC’s coverage:
“People born in the 80s and 90s are at double the risk for developing cancer of the colon and four times the risk for developing cancer of the rectum compared to people born decades earlier like the 40s and 50s,” said Dr. Richard Wender, chief cancer control officer for the American Cancer Society.
“We’re actually seeing colorectal cancer developing in people in their teens, which is something that was extraordinarily rare in the past, and it’s all too common today,” Wender told NBC News.
Missing from all of these stories, however, is any quantification of the actual rate of colon cancer in these groups, which might help readers understand what the ACS spokesman means by “all too common.”
As the New York Times noted last year, a person who was born in 1950 had a three in a million risk of developing colon cancer in their twenties, compared with a five per million risk for someone born in 1990. The risk of rectal cancer for someone in their twenties increased from 0.9 per million for those born in 1950, compared with 4 per million for someone born in 1990.
Those increases are in the same ballpark as the risk of being struck by lightning.
For comparison, the incidence of colon cancer in those over age 50 was 119 per 100,000 in 2013 — several orders of magnitude higher.
Perhaps more importantly, few of the stories I looked at raised any concerns about the evidence supporting the new guidance, even as they noted that other professional groups are sticking with their current recommendations to start screening at age 50.
Kenny Lin, MD, MPH, professor of clinical family medicine at Georgetown University, offered a counterpoint to predictions that the new guidance would save lives.
“The rationale for screening at an earlier age is that the incidence of colorectal cancer is higher [than in the past]… so there are more cancers to be found by screening,” he wrote in an email. But he pointed out that this rationale makes some assumptions — notably that the cancers being found in younger adults behave the same way, and can be treated as effectively, as those in older adults. It also assumes that outcomes are better when these cancers are found via screening, before they start causing symptoms (e.g. rectal bleeding).
“If either assumption doesn’t hold true, then earlier screening could fail to improve colorectal cancer mortality in real life, no matter what the models say,” Lin said.
Richard Hoffman, MD, MPH, director of the Division of General Internal Medicine for the University of Iowa Carver College of Medicine, pointed out another assumption baked into the guidelines — that patients will follow the ACS screening recommendations down to the letter and seek follow-up screens at the appropriate intervals.
“Given that we are being told that only 2/3 of adults 50 to 74 are adherent [with screening recommendations], this raises questions about the potential effectiveness of screening younger patients, especially with uncertain insurance coverage,” Hoffman said.
Internists Pieter Cohen, MD and Michael Hochman, MD raised other concerns in their Updates in Slow Medicine email newsletter, noting the data wasn’t from a clinical trial.
The change … is not based on the results of a new clinical trial but rather modeling studies based on increasing prevalence of colorectal cancer among US adults in their 40s. The updated guideline encourages clinicians to discuss different screening modalities with patients, but, unfortunately, does not suggest counseling patients that there are a variety of expert opinions on when to start screening and that beginning screening before age 50 has known risks but only theoretical benefits.
Although there are several ways to screen for colon cancer, some professional groups, including the American Gastroenterological Association, endorse colonoscopies over other methods. But is this the safest approach? Cohen and Hochman point to recent data that shows “you are about 8 times more likely to end up in the hospital within a week of your screening colonoscopy than you are to be saved from colon cancer death over 10 years.”
USA Today was one of the few outlets that called attention to these potential harms, which include bowel perforation and complications from anesthesia. It also featured an extensive discussion of costs, and noted the ACS recommendation was “qualified” due to limitations in the evidence. According to an ACS guideline author, this means that “we hope that doctors will look at this and at least start discussions of colorectal cancer screening with their 45-year-old patients.”
However, Hoffman wondered whether clinicians have enough data to make these kinds of discussions meaningful. He noted that truly personalized decision making “requires informing patients about the benefits and harms of early screening and it’s not clear that we have sufficient clinical data to support these decisions.”
To their credit — and reflecting the emphasis in the ACS news release announcing the guidelines — most stories generally did a good job of discussing noninvasive colorectal cancer screening options like blood and stool tests.
But overall, few outlets challenged the narrative that more lives would be saved with an earlier start to screening and that the benefits would outweigh the harms. Those claims are speculative and may be plausible, but they are not yet proven. Some experts believe the attention focused on younger patients could be more effectively channeled elsewhere.
“Something like 1/3rd of the population age 50-75 isn’t up-to-date on any method of colorectal cancer screening,” Lin said. “The benefits of extending the start-screening age by 5 years, even if they exist, pale compared to the potential benefits of getting more people in the universally agreed-upon age range screened.”