By Cyrus Moulton,Northeastern University

Credit: Unsplash/CC0 Public Domain

Age 45: You've made it to middle age, you're ideally entering your prime earning years and, if you're like most adults, your doctor tells you that it's time to consider your first colonoscopy to screen for colorectal cancer.

But why age 45? It's the same age at which the American Cancer Society (ACS) recommends that women begin getting annual mammograms. For most men, discussions with their doctor about prostate cancer screenings typically begin around age 50.

Neil Maniar, director of the master of public health program and professor of practice in public health and health sciences at Northeastern, explained that colorectal cancer is "quite treatable" if detected early, and about 80% of colorectal cancers start as precancerouspolyps, small clumps of cellsthat form on the lining of the colon. Polyps can be removed before they potentially turn cancerous.

While for many years, those precancerous polyps were most likely to be seen in adults 50 and older, there's been "a significant surge" in colorectal cancer cases among younger and younger populations, Maniar said.

According to CA, the flagship journal of the ACS, colorectal cancer cases declined by 0.9% annually between 2013 and 2022, but incidencerates increased by 3% annuallyin adults ages 20 to 49 and by 0.4% annually in adults ages 50 to 64.

"At age 45, the incidence of colorectal carcinoma now mirrors what it looked like a few years ago when people age 50 had the same risk," said Ram Hariharan, associate teaching professor of software engineering and information systems who focuses on applying artificial intelligence to health care and studies human aging and health.

For breast cancer, screening mammography in women ages 40 to 69 is associated with areduction in breast cancer deathsacross a range of study designs, the ACS notes.

Still, the age guidelines are not set in stone.

"If your relatives have had cancer, if you have a genetic condition that predisposes you to cancer, or if you are in an occupation that predisposes you to cancer, everything changes," Hariharan said, noting that individuals in such situations should be screened earlier than the age guidelines suggest.

Maniar agreed, saying the age guidelines are "important, but they're not one of those things where it applies to everyone."

Guidelines are also periodically revised. For example,the ACS, which routinely reviews data and trends and examines where it's likely to see an increase in cases of some preventable cancers or cancers for which effective screening is available, revised itsbreast cancer screening guidelinesin 2015. It began recommending that women at average risk—meaning they have the same baseline risk of developing a condition as most people in the population—undergo annual mammograms atage 45 rather than age 40, as the previous guidelines had stated.

The American College of Physicians, a national organization of internal medicine physicians,revised its guidelines in April, recommending that all average-risk women ages 50–74 undergo biennial mammography screening for breast cancer.

As for colorectal cancer screenings, the U.S. Preventive Services Task Force (USPSTF)—a panel of volunteer experts who determine which medical screenings and preventive procedures insurance companies must cover for millions of Americans at no cost—in May 2021 changed itsscreening recommendationfrom age 50 to age 45for adults at average risk.

Maniar said the decision-making behind age guidelines is "all part of a coordinated system" and "all tied to the data."

"It's reactive in the sense that, as the data starts to indicate the need to address some of these guidelines and recommendations, the [USPSTF] would then respond to that," Maniar said.

Even so, "The best way to look at [guidelines] is like a balance and the idea of a tipping point," Hariharan said.

Hariharan explained that one side of the hypothetical scale features the number of lives saved by conducting a screening test such as a mammogram or colorectal screening test. The other weighs the costs, Hariharan said, such asoverdiagnosis, or the diagnosis of a medical condition that would never have caused any symptoms or problems;false positives, where a test incorrectly indicates the presence of what it is searching for; and inconvenience for healthy people who do not have the disease and must undergo those procedures.

"This tipping point is calculated by a mathematical model and is the point at which the disease incidence goes up and it becomes worth giving the screening test, as you will save more lives weighed against all these other factors," Hariharan said.

But just because a mathematical model is used to determine screening ages doesn't mean that actuaries are making health care decisions, Hariharan and Maniar said.

For Maniar, the issue takes on some urgency because of what he sees as the task force's independence being undermined by political considerations.

The Trump administrationfired two leadersof the task force in May, and Health and Human Services Secretary Robert F. Kennedy Jr. has "quietly undermined" the task force's work, including by not replacing members whose terms ended in December and postponing the task force's meetings indefinitely, according to reporting by The New York Times.

"Is there a reason to question (their recommendations)?" Maniar asked rhetorically. "I would hope not, but I think it's troubling when there's been so much disruption."