“There will be some men who would say, ‘Let’s do it anyway,’ and other men who say, ‘If we don’t need to do it, let’s not do it,’ ” Dr. Calonge said.

The guidelines focus on the screening of healthy older men without symptoms and will not affect treatment of men who go to the doctor with symptoms of prostate cancer, like frequent or painful urination or blood in the urine or the semen.

Studies of the value of prostate cancer screening for younger men have produced mixed results, but a major clinical trial under way in Europe will try to determine whether there is any value, in terms of longer life expectancy, to screening this group for prostate cancer. Those results may be published as early as next year.

While the verdict is still out on younger men, the data for older men are more conclusive, experts say. The American Cancer Society and the American Urological Association both say annual PSA screening should be offered to average-risk men 50 and older, but only if they have a greater than 10-year life expectancy.

Recently, Swedish researchers collected 10 years of data on men whose cancer was diagnosed after the age of 65 and found no difference in survival among those who were treated for the disease and those whose cancers were monitored but treated only if the cancer progressed. The finding suggests that for most men, stopping screening at 75 is a safe option.

“If someone has made it to the age of 75 and they don’t have an elevated PSA, the likelihood of them developing clinically significant prostate cancer in the last 10 to 15 years of their life is pretty low,” said Dr. Peter C. Albertsen, professor of urology at the University of Connecticut Health Center. “The downside risk begins to outweigh the upside at the age of 75.”

Some studies suggest that as many as half of men 75 and older have clinically insignificant prostate cancer that is unlikely to affect their health but may be found through a biopsy. If the disease is detected as a result of screening, the men may be actively treated with radiation or hormone therapies, or may endure the stress of “watchful waiting” to see if the disease progresses.