Screening tests for cancer are often a good idea. Early detection of unapparent cancers of the breast, cervix or colon saves thousands of lives every year. Routine check-ups for these and certain other cancers at recommended intervals are part of a healthy adult lifestyle.

But screening of men for cancer of the prostate gland, particularly among men over age 75, isn’t so clear-cut.

So says a new report from the U.S. Preventive Services Task Force, an independent panel of experts in prevention and primary health care that judges the effectiveness of screening tests and other clinical preventive services.

The task force conducted a rigorous and impartial review of all available evidence on the benefits and harms of the primary blood test used to detect prostate cancer in its silent, early stages: the prostate-specific antigen (PSA) test.

The experts concluded that for men 75 and older, this test provides few health benefits, but can lead to substantial physical and psychological harm. For men younger than 75, the task force determined that there is insufficient evidence to recommend for or against screening for prostate cancer with the PSA test.

Why are the experts so reluctant to advocate screening?

Certainly prostate cancer is a serious public health problem. One in six men alive today will develop the disease during their lifetimes. More than 200,000 American men are diagnosed with it each year, and more than 27,000 of these will die from it.

There is no question that increased awareness of prostate cancer and widespread use of PSA screening in recent years has enabled many men to beat the disease, when otherwise they would have died. Why not promote such screening for every man?

The reason to withhold screening among those over 75 is the slow-moving nature of most prostate cancers. Cancers detected by screening with the PSA test generally take years to affect health. Those that grow serious enough to cause death typically take more than 10 years to do so.

The life expectancy of 75-year-old men today is about 10 years. During that time they are more likely to die from heart disease, strokes and other causes than from slow-growing prostate cancers detected only through screening.

In other words, older men who have the disease in its early stages are more likely to die with prostate cancer than from it.

The same can be said for younger men with chronic medical problems that will shorten life expectancy to 10 years or less. They too are unlikely to live any longer because they undergo screening for prostate cancer.

What they risk when they obtain screening for prostate cancer with the PSA test is physical harm and anxiety from the follow-up tests and treatments that may be necessary when the initial results point to a possible problem. Common complications from the treatment of prostate cancer include urinary incontinence and impotence.

For many men in the last decade of life, untreated prostate cancers might never affect their health or well-being. For them, it may be better not to know.

For men between the ages of 50 and 75, the best approach is an open discussion with health-care providers on the how the benefits and possible harms of screening balance out. Any decision about prostate cancer screening should be an informed decision.

— Jason Eberhart-Phillips, M.D., is the El Dorado County health officer. He can be reached at jeberhart-phillips@edcgov.us.