There is no question that cancer screening has helped many people live longer and healthier lives. Oncologists see the devastating effects cancer can have on patients and families, and outcomes often seem better when the cancer found is at an earlier stage. This observation gives us hope that screening asymptomatic individuals will detect cancers at a more treatable stage and result in better outcomes. But what science do we need before encouraging primary care physicians to routinely screen for a specific cancer? For any preventive service, most individuals who receive the service will neither benefit nor be harmed, but there will always be some who benefit and some who are harmed. We should use a preventive service when good science tells us that across the population served there is more benefit than harm. The US Preventive Services Task Force (USPSTF, or “Task Force”) aims to help physicians and patients identify those services for which that is the case.
The Task Force is an independent, volunteer panel of national experts in prevention and evidence-based medicine that makes recommendations for use in primary care settings. Its recommendations are based on a systematic review of the latest scientific evidence about both the benefits and the harms of screening. A judgment is made about the scientific certainty of the magnitude of both benefits and harms, and when at least moderate certainty in the evidence is present, a recommendation is made based on the overall balance of benefits and harms.
Few cancers meet rigorous scientific criteria for routine screening. Often the science is insufficient, but occasionally science tells us that screening does more harm than good. Unfortunately, the current prostate-specific antigen (PSA) test, used to screen for prostate cancer, is in this latter category.
Among the largest trials of PSA screening, the multicenter Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, conducted in the United States, showed a non–statistically significant increase in prostate cancer mortality in the screened population, while the European Randomized Study of Screening for Prostate Cancer trial showed a statistically significant absolute reduction of 0.10 prostate cancer deaths per 1,000 person-years after a median follow-up of 11 years. However, the reduction in prostate cancer–specific mortality seen in the European trial occurred in the context of a significant increase in the number of cancers diagnosed and treated in the screened group, and the difference in all-cause mortality was not statistically significant (19.1% in the screened group and 19.3% in the control group).
Much of the morbidity resulting from prostate cancer is a consequence of the diagnosis and management of the disease, rather than of the disease itself, and many screen-detected cancers would never become apparent in the patient’s lifetime in the absence of screening. Most men with abnormal PSA levels do undergo a prostate biopsy, and in the United States, 90% of those with PSA-detected prostate cancer do receive treatment. Of 1,000 men screened, 2 to 3 will have a serious complication from treatment, such as a venous thromboembolism, myocardial infarction, or stroke, and a small number will die from treatment complications. As many as 40 out of 1,000 men screened will experience erectile dysfunction, urinary incontinence, or both. In addition, about 30 to 40 men in 1,000 will also experience less serious harms from a prostate biopsy, such as pain, fever, bleeding, infection, or hospitalization. The USPSTF judged that these harms outweigh the benefits and recommended against prostate cancer screening for men of all ages.
The balance of benefit and harms could shift with a screening test that better differentiates men who have cancer from those who don’t, with tests that better differentiate cancers that are likely to threaten a man’s health from those that are not, or with treatments that result in fewer serious adverse effects. Until we improve the testing and treatment, the Task Force believes that primary care physicians should not feel obligated to offer PSA testing. If a patient raises the issue or requests the test, we urge healthcare professionals to be forthcoming about the facts about prostate cancer risk, the relatively small benefit of detection, and the significant harms associated with diagnosis and treatment. Whether or not to be screened is a decision each man should make with his clinician, based on his values and preferences.
The Task Force has no ability or inclination to restrict access to the PSA test, but rather wants to help each man make an informed decision based on the available facts. The Task Force’s recommendation against PSA screening for prostate cancer is based on the best available science and the knowledge that, while we all want to prevent suffering and death from prostate cancer, PSA screening simply does not get us there.
The authors have no significant financial interest or other relationship with the manufacturers of any products or providers of any service mentioned in this article.
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