But the PSA test offers a small potential for benefit -- with clear potential for harm. That is, there is moderate certainty of the test reducing the chance of men dying of prostate cancer, but many men will experience potential harms simply from the screening.
For example, PSA screening -- a blood test that looks for elevated levels of a protein -- can result in a positive screen that requires diagnostic testing, which can lead to infection as well as treatment complications such as incontinence, impotence, bowel injury and even death. And this could occur even in the absence of prostate cancer: PSA has been shown to have a high false positive rate and a high false negative rate -- literally missing as many prostate cancers as it finds.
That is why the US Preventive Services Task Force issued a new draft prostate cancer screening recommendation Tuesday.
It proposes shifting from the task force's recommendation against routine prostate cancer screening to a recommendation for informed and shared decision-making in which the physician and patient discuss the real risks of harm and the potential for lifesaving benefit before deciding on screening.
It's not a shift to be taken lightly: The task force is known for being conservative and orthodox in interpreting scientific data and trends in medicine. It is a highly respected, highly skilled group of public health experts who review scientific studies and make recommendations on disease prevention and screening. Following a well-established process, it reviews the scientific evidence, issues a draft guideline for the public and solicits comment. The task force will issue a final recommendation after consideration of the public comment.
The new recommendation aligns the task force with the American Cancer Society, the American College of Physicians and the American Urological Association, all of which acknowledge the PSA test's potential for harm and possibility of benefits, and advocate shared or informed decision-making.
What does shared or informed decision-making mean? Doctors should discuss the issues with male patients and help them decide whether to be screened. These are complicated issues for a patient to navigate; it is imperative the patient play a role since it is his life that is affected. Some, such as the American Cancer Society, suggest the discussion should start at age 50; others, such as the task force, say it should start at 55.
The fact that there are harms has been difficult for many advocates of prostate cancer screening to accept. The PSA test became available in the mid-1980s. Several clinical studies demonstrated that the test helped find localized prostate cancer. This led to widespread screening.
Celebrities, sports personalities and politicians became spokesmen encouraging screening. There was promotion of screening, not just by doctors to their patients but by clinics, patient advocacy organizations and even an adult diaper manufacturer. Screening was done at health fairs, state fairs, shopping malls and even on the floor of the 1992 Republican National Convention
in Houston. Men who were diagnosed with prostate cancer were rushed to treatment with surgery, radiation or hormones. Many hospitals put prostate cancer screening and treatment into their business plans, and it became a significant profit center.
Enthusiasm for the test was premature: The first studies to show that prostate cancer treatment saved lives were not published till 1997, more than a decade after the start of the screening frenzy. Studies to show that screening was associated with a reduction in risk of death were not published until 2009. Even now results showing the benefit of screening are inconsistent. Some well-conducted clinical trials do not show benefit, while all studies show harm.
Indeed, it is fair to say the harms of prostate screening are better proven than the benefits, although benefits likely do exist. One proven harm is overdiagnosis. Some cancers, ironically the ones easiest to diagnose and cure, are so slow-growing they are of no threat to the patient: They do not need to be cured, as they would never do harm if left alone. One epidemiologic study suggests that more than 1 million American men received unnecessary treatment over the past 25 years.
Indeed, the US Preventive Services Task Force is responding to increasing evidence of an improvement in pathological interpretation, which allows for better prediction of the cancers that do not need treatment. Recent studies of health practices show a movement away from immediate aggressive therapy for all prostate cancers and increasing use of "active surveillance" or monitoring when PSA testing finds a low-risk cancer. That means fewer harms from surgery and radiation.
Hopefully, we will all embrace shared or informed decision-making. Some men who are concerned about prostate cancer will elect to be screened, and others who are less concerned will not; doctors should support either decision. Once diagnosed, hopefully patients and their physicians will not rush into treatment but explore and consider all reasonable options.
Good scientific research has bought about improved understanding of cancer and the limitations of screening tests, diagnostics and treatment. This is leading more and more to professional guidelines that respect patient preference and put the screening decision in the hands of the patient.