Many men in their 80s get regular blood tests for prostate cancer even though there’s no evidence the tests will benefit them, according to a new study.

In older men, finding hidden prostate cancer might not be helpful, because the cancer might not shorten their lifespan. But once it’s discovered, a very early-stage cancer usually leads to painful and expensive medical encounters.

So with elderly men, screening “makes no sense,” Dr. Peter Albertsen, a prostate cancer researcher at University of Connecticut Health Center in Farmington who was not involved with the current study, told Reuters Health.

The researchers also found that men in their 70s were almost twice as likely as men in their 50s to have a blood test that looks for signs of prostate cancer - even though younger men have the best chance to benefit from screening.

“Those younger men are the ones the test was designed for,” Dr. Scott Eggener, one of the study’s authors from the University of Chicago Medical Center, told Reuters Health. But older men “are far more likely to see their doctor regularly,” and doctors may be used to ordering the prostate cancer blood tests in these men without really thinking about it, he said.

The findings, published in the Journal of Clinical Oncology, come amid a debate in the medical community on whether routine cancer screening can extend lives.

The blood test in question looks for a protein produced by the prostate called prostate-specific antigen, or PSA. As the National Institutes of Health explains on its web site, the higher a man’s PSA level, the more likely it is that he has prostate cancer. A man can have an elevated PSA level without having cancer, though.

To estimate national rates of PSA screening, Eggener and his colleagues consulted data from two country-wide health surveys that had been conducted in 2000 and 2005. The surveys asked almost 15,000 men whether they had been screened for prostate cancer in the past year.

Twenty-four percent of men in their early 50s said they had been screened. More men reported recent screening as age increased, with about 46 percent of men in their early 70s having been screened. Rates declined again once men passed the age of 74, but about 25 percent of men age 85 and older still said they had been screened in the past year.

Scaling those numbers up to reflect the entire U.S. population, the authors calculated that about 1.5 million men in their 80s and older had a PSA screening test recently.

While catching prostate cancer early can prevent the disease from progressing, men with a positive reading are subjected to biopsies and sometimes treatment, involving uncomfortable procedures that carry risks of complications and side effects.

Especially with older men or those with other chronic diseases, it’s possible that the risk is for nothing, and that having undetected cancer wouldn’t have cut any time from their lives.

Screening patients who won’t really benefit also adds unnecessary costs to the health system. The average cost of a PSA test is estimated to range from $70 to $400 dollars. Medicare will pay for 80 percent of the cost, but some private insurance companies won’t cover PSA screening at all.

Dr. Steven Woloshin, who studies the risks and benefits of cancer screening at Dartmouth Medical School in Hanover, New Hampshire, said that even in younger men, there is not much evidence that prostate screening can prevent deaths.

“There’s a small chance or maybe no chance of benefit,” Woloshin, who also did not participate in the new study, told Reuters Health, “but there’s certainly a possibility of harm” in the form of unnecessary tests and treatment.

The U.S. Preventive Services Task Force, a federal expert panel, reported in 2008 that the benefits of screening for prostate cancer in men younger than 75 are “uncertain,” and that the harms probably outweigh any benefits for men 75 and older.

It’s hard to know if that message is being communicated to men who are considering screening, Woloshin said.

Eggener said that men should be aware of the benefits and risks of PSA screening, and that neither patients nor doctors should assume that getting screened is always the right way to go.

“The optimal way of doing it is for both patients and physicians to have a meaningful conversation about, ‘should I get this test or should I not?’” Eggener said.

SOURCE: Journal of Clinical Oncology, online March 29, 2011.