A new study conducted by the United States Preventive Services Task Force (USPSTF) suggests many older adults are being screened for cancer who no longer need to be.
The USPSTF recommends that people at average risk of cancer get colorectal cancer screening through age 75, breast cancer screening through age 74, and cervical cancer screening through age 65.
In general, above those ages, people have a greater likelihood of being harmed by than benefiting from these tests, explained Barry Kramer, M.D., M.P.H., of NCI’s Division of Cancer Control and Population Sciences, who was not involved in the study.
The term "overscreening" is used to describe the use of such tests past the point where they are likely to provide a net benefit.
People often aren’t aware that there are potential harms from cancer screening, explained Jennifer Moss, Ph.D., from Penn State University, who led the new study, which was funded in part by NCI and published July 27 in JAMA Network Open. These harms can include false-positive test results that lead to unnecessary follow-up procedures.
“But what we’re particularly worried about for older adults is the harm from the test itself. All of these screening tests are medical procedures that have potential side effects,” Dr. Moss said. This risk of harm is highest for invasive tests, such as colonoscopy.
Studies have shown that the overall benefits of screening, such as detecting cancer earlier when it's potentially easier to treat, outweigh the likelihood of harms in younger adults. However, the harms increase as people age.
Screening tests usually pick up slower growing cancers. “For some tests, it can take 10 to 15 years, or even more, to reveal their benefits. The older you are, the less likely you are to reap those benefits,” said Dr. Kramer. As people grow older, the more they are likely to die of another cause before a cancer that might have been detected early on a screening test would have caused symptoms.
“The harms, however, are front-loaded: they often occur at the time of the test or shortly thereafter,” he said.
“That's why these recommendations are in place, to make sure that people who get screened are going to benefit and that the likelihood of the risks or harms are minimized to the extent possible,” Dr. Moss added.
Widespread Testing, Regardless of Health
Reports from single hospitals have suggested that many older adults are getting overscreened. To get a better idea of these trends nationwide, Dr. Moss and her colleagues used data collected in 2018 by the Behavioral Risk Factor Surveillance System, a yearly national survey conducted by the Centers for Disease Control and Prevention.
They reviewed survey responses from more than 175,000 older women and men whose average age was 75 and recorded the ages at which participants last reported receiving cancer screening tests. They also looked at whether participants lived in a metropolitan area, because access to cancer screening can differ between urban and rural regions.
The researchers also used self-reported health information from the survey to estimate participants’ risk of dying from any cause within the next 10 years.
More than 80% of survey participants lived in a metropolitan area, and almost three-quarters reported good, very good, or excellent health.
Most participants reported having been screened for one or more cancer types “after they had ‘aged out’ of the recommended range for routine cancer screening,” said Dr. Moss. “We found that overscreening was incredibly common. Overall, 45% to 75% of older adults were getting these tests [past the recommended age].”
Fifty-nine percent of men reported being screened for colorectal cancer after the age where they would be expected to benefit. And most women reported being overscreened for one or more cancer types: 74% for breast cancer, 56% for colorectal cancer, and 46% for cervical cancer.
Women who lived in metropolitan areas were more likely to be overscreened for each of these cancers than those in rural communities. The same was not true for men, however.
Because of the limited availability of hospitals and other health care facilities, people who live in rural areas often have challenges getting screened. While this can reduce overscreening, it can also prevent people from getting appropriate screening tests when needed, the study authors explained. Why this trend wasn’t seen for colorectal cancer screening in men in this study was not clear.
People’s projected life expectancy did not seem to influence whether or not they received screening tests.
“We expected that as mortality risk was higher, and therefore life expectancy was lower, that people would not be overscreened as much,” Dr. Moss said. “But we didn't see a lot of evidence for that. It doesn't appear that someone's overall health really influences this decision…so that was surprising.”
Testing Beyond Screening
The USPSTF recommendations—and most recommendations from professional societies—are for people at average risk of cancer. The survey did not ask whether participants had an increased risk of cancer. For example, people with some inherited gene mutations, or with a family history of cancer, may be encouraged to continue screening at older ages.
“And if you’ve had cancer in the past, or had abnormal results on [previous] cancer screening tests, there are different guidelines for whether or not you should continue getting screened and for how long you should continue getting screened,” explained Dr. Moss. But such people were likely a minority in the current study, she added.
The data also didn’t capture if a test was done because someone reported symptoms. Those types of diagnostic tests remain vital, no matter someone’s age, explained Dr. Kramer.
Even during the current pandemic, if you find a lump or experience bleeding or other concerning symptoms, “get to your doctor,” he said. “That’s not screening—that’s workup of a potentially serious problem.”
But overall, the study results highlight that better education about cancer screening in older adults is needed, for both clinicians and the public, said both Dr. Moss and Dr. Kramer.
“When we hear public service announcements or people talking generally about cancer screening, we don't hear a lot about the age when you should stop getting screened,” Dr. Moss said. Among both clinicians and the public, she continued, “I think that there's pretty low awareness of when older adults should graduate out of screening.”
“Many practitioners are not aware of what the guidelines are,” agreed Dr. Kramer. But also, he added, conversations about stopping screening are difficult ones, particularly if a clinician has a long-term relationship with someone.
“A physician who for years has been ordering tests for their patients may find it very difficult to say, 'You've reached the point where you're not likely to live long enough [to benefit],’” he said.
A Need for Informed Decision-Making
It’s also likely that a subset of older adults with good health and longer life expectancy would benefit from continued screening, but it’s not yet clear exactly who those people are, said Dr. Moss. More research is needed in this area, she added.
“When estimating the balance between benefits and harms, there’s often an upper age range. But that age range, the upper limit, is not fixed in stone as years go by,” said Dr. Kramer.
More research is also needed into when and how to have conversations about stopping screening, added Dr. Moss.
“There's a lot that we can learn from practice around lung cancer screening and prostate cancer screening,” she said. “Both of those screening tests are not really recommended for everyone who walks through the door. You're supposed to talk to your provider about whether or not it's appropriate for you, what your risks are, and what would the risks be of the test itself.
“We’ve done some focus groups with older adults about how people would want to talk about stopping screening with their provider,” she explained. “And a lot of older adults are really willing to [have these conversations]. They want information that’s very targeted to them and their personal health risks.”