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Be Well

Screening Tests: How Old Is Too Old?

by John Swartzberg, M.D.  

The Wellness Letter has delved into many of the ongoing and often heated debates about cancer screening tests—for instance, about when to start having mammograms and how often, about the various kinds of colorectal cancer screening tests, and about the usefulness of PSA testing in general.

As we’ve reported, guidelines from the U.S. Preventive Services Task Force and most other expert groups advise people age 75 and older who have previously had normal results to discontinue screening for prostate, breast, and colon cancer (the cutoff is 65 for Pap tests for most women) because the benefits for this age group are unlikely or at least uncertain.

That has led some healthy older readers to write to us, questioning this advice to stop screening. Stopping is indeed a hard decision to make—and not the right one for everyone.

There’s no doubt that far too many older Americans continue to dutifully get screened—out of habit or fear, out of hope that they’ll live long enough to benefit, or simply because their doctors advise it. For instance, some studies have found that about 40 to 60 percent of men over 74 (with no symptoms or history of prostate cancer) continue to get screened with PSA tests, as do 25 percent of men over 84. The chances of being diagnosed with cancer and dying from it rise dramatically with age. So it is tempting to think that older people, in particular, should be screened.

However, randomized trials on screening tests have included few, if any, people over 75. The limited evidence we do have strongly suggests that the benefits of early detection and subsequent treatment of cancer decline sharply in older people, and the potential harms increase. Frail older people are at elevated risk for adverse effects from some screening tests (such as colonoscopy) and, if results are abnormal, for complications from the treatments.

In addition, there’s an increased chance that screening older people will lead to the diagnosis and treatment of cancers that would never pose a threat to their lives and may not even cause symptoms. That is, the older you are, the more likely it is that you will die with the cancer rather than from it.

Here’s where a crystal ball would come in handy. The guidelines generally say that people with a life expectancy of less than five years should stop being screened; some say ten years. But studies show that people are bad at estimating how much longer they’re likely to live (or don’t even want to discuss this), and often their doctors are not much better at predicting.

Sure, it’s clear that a frail 75-year-old living in a nursing home with congestive heart failure and a recently broken hip or dementia shouldn’t be screened for cancer. On the other hand, it may be appropriate for a healthy, active 80-year-old to continue screening. Most of us, however, eventually fall into a gray area where the calculation to stop or continue screening becomes more difficult.

Your decision will largely depend on your values and preferences, especially concerning medical interventions. If you are over 75 or are younger but have a life-limiting illness, you should talk with a health care provider about the pros and cons of screening and get individualized advice. It’s perfectly okay to stop, but it’s also okay to continue. It’s your choice—but don’t continue just because the screening mentality has become ingrained or because of the misguided belief that more is always better when it comes to health care.