Prostate Cancer Screening: Where Do We Stand?
Does PSA-based prostate cancer screening lead to less deaths from the disease? CURE explores both sides of the debate.
PUBLISHED September 29, 2016
Prostate cancer screening using PSA-based testing remains controversial four years after the U.S. Preventive Services Task Force (USPSTF) recommended against it for healthy men of any age. Advocates of the approach say it saves lives through early detection, while critics say it leads to unnecessary medical procedures, such as prostate biopsies, that can cause potential complications and harmful side effects, as well as treatment of tumors that would have never caused symptoms or shortened lives. The latter can leave men incontinent or impotent — sometimes both.
A PSA test is a blood test that measures the level of a protein made by cells in the prostate gland. PSA levels rise when there’s a problem with the prostate, including prostate cancer. The problem is that PSA is also elevated in men with several other non-cancerous conditions, such as an enlarged benign inflammation of the prostate. In fact, three out of every four men who have a high PSA do not have prostate cancer. Until recently, many doctors encouraged yearly PSA screening for men beginning at age 50. Some organizations also recommended that men with a higher risk of prostate cancer, including African-American men and men whose fathers or brothers had prostate cancer, have PSA screening beginning at age 40.
Those ideas were challenged by the USPSTF’s 2012 recommendation, which was based on findings from the Prostate, Lung, Colorectal and Ovarian (PLCO) trial, a $400 million study to determine whether certain screening tests can help reduce the number of deaths from several common cancers, including prostate cancer. Men in the study received either prostate cancer screening, which included PSA testing, or usual care at their doctor’s office. When PLCO researchers compared the two groups, they found no difference in the mortality rate, which was interpreted to mean that PSA screening is ineffective at reducing prostate cancer-related deaths and that men were unnecessarily exposed to the potential harms of treatment.
Nevertheless, many experts, including the American Urological Association, continue to believe that not using PSA testing will result in the deaths of more men from prostate cancer, and they advocate the use of PSA testing for early prostate cancer detection.
That belief got a boost recently when PLCO findings were called into question. After re-examining the study’s methodology, researchers from New York-Presbyterian and Weill Cornell Medicine found significant errors in how the study was designed: About 90 percent of men in the control arm of the study had received PSA testing before or during the trial, meaning that comparing the control and intervention arms of the trial is not useful to evaluate the effectiveness of PSA screening.
This kind of conflicting evidence has prompted the USPSTF to reevaluate its current recommendation against PSA-screening. CURE will report back once its final recommendation is issued.