Experts generally recommend against routinely using PSA blood tests to screen elderly men for prostate cancer, but using a strict age cutoff for when to stop screening may not be the best route either, a new study suggests.

Right now, there are conflicting opinions as to when men should stop being screened for prostate cancer using PSA, or prostate-specific antigen, tests.

Certain medical groups, like the American Urological Association and the American Cancer Society, say that PSA screening should be an option - though not a routine procedure - for any man whose health is good enough that he can expect to live at least 10 more years.

But 2008 guidelines from the U.S. Preventive Services Task Force (USPSTF) - an independent panel of medical experts appointed by the federal government - recommend against screening any man age 75 or older, regardless of his health.

The central problem with prostate cancer screening is that most prostate tumors are slow-growing and would not be deadly even without treatment. So screening can lead to unnecessary treatment of cancers that would never had been life-threatening, along with treatment’s side effects.

According to the USPSTF’s 2008 statement, there is “moderate certainty” that for men age 75 or older, the potential harms of prostate cancer screening outweigh the benefits.

For the new study, researchers looked at whether, before the 2008 guideline, U.S. doctors were appropriately using elderly men’s health and life expectancy in recommending PSA testing.

Using data from 718 men age 75 and up who responded to a 2005 national health survey, the researchers found that 52 percent said they had had a PSA test in the past two years. Men who rated their own health as “fair” or “poor” were half as likely to have been tested as those who described their health as “very good” or “excellent.”

Still, a substantial number of men who would not be expected to benefit from PSA screening were being tested nonetheless. Of the 182 men expected to live less than five years - based on their age and reported health status - 42 percent had had a recent PSA test.

That compared with 65 percent of the 214 men expected to live more than 10 years.

The findings, reported in the Journal of Urology, suggest that limiting PSA screening to men younger than 75 would prevent unnecessary testing of some men who would not benefit from treatment, according to lead researcher Dr. Karen E. Hoffman, of the University of Texas M.D. Anderson Cancer Center in Houston.

“However,” she told Reuters Health by email, “the results also suggest a strict age cutoff may preclude the early detection of biologically aggressive prostate cancer in older men with a long life expectancy who may benefit from early detection and treatment of high-grade (aggressive) prostate cancer.”

The study has its limits, Hoffman and her colleagues acknowledge - including the fact that it relied on men’s self-reported health and PSA screening history. Still, they say, the findings point to pros and cons of setting a strict age cutoff for PSA screening.

More research, the investigators write, is needed to understand the impact of using an age limit when it comes to screening healthy men.

The bottom line for older men, Hoffman said, is that they should talk with their doctors about the risks and benefits of PSA screening “in the context of their overall health status and their individual preferences.”

But while doctors might recommend PSA screening to some men age 75 or older, there is no evidence yet that it lowers their risk of dying from the disease or extends their life expectancy overall.

Past clinical trials on prostate cancer screening have not included men in that age group, Hoffman said.

SOURCE: Journal of Urology, May 2010.