New Research Questions Recommendations Regarding PSA Tests for Prostate Cancer Screening

Research results favor testing for prostate specific antigen (PSA) levels for detection of prostate cancer. PSA tests can reduce the number of fatal cases of prostate cancer by detecting disease early. These results contrast the US Preventive Services Task Force 2012 recommendations that were based on a landmark national study.¹

In a letter to the editor of the New England Journal of Medicine, researchers encouraged PSA tests and reconsideration of the guidelines after discovering an error in the landmark study. According to this study, the Prostate, Lung, Colorectal and Ovarian (PLCO) trial that assessed the value of PSA screening erroneously reported no difference in mortality rates between men who underwent PSA screening and men who did not, indicating PSA screening is ineffective.

As a result of the PLCO trial, several US organizations now recommend against PSA screening.

“We expect this article to have a profound impact on the debate over the value of PSA screening,” said Jim Hu, MD, director of the LeFrak Center for Robotic Surgery at New York-Presbyterian/Weill Cornell Medical Center and the Ronald Lynch Professor of Urologic Oncology at Weill Cornell Medicine, New York City.

“While there are risks of overdiagnosis and overtreatment associated with PSA testing, it can play an important role in preventing prostate cancer deaths as part of a personalized approach to cancer screening. We’re going to have to reconsider this issue.”

Prostate cancer is the second leading cause of death from cancer among American men. It is also second only to skin cancer in how common it is in men. The PLCO trial compared mortality rates from prostate cancer in a group of men who underwent PSA screening tests and a group of men who did not undergo PSA screening tests. The PLCO study found no differences in mortality rates from prostate cancer between the 2 groups.

This study examined the PLCO trial’s methodology, discovering that data from many men in the control group who underwent PSA tests were not included as tested in the study report. This caused the study results from the PLCO trial to be misinterpreted. In reality, 90% of men in the control arm had undergone PSA testing such that comparing the control arm to the intervention arm was not informative for assessing the usefulness of PSA tests.

“We demonstrate that the PLCO study did not compare a group of men who received PSA screening to a group of men who were not screened, but compared men who were screened to other men who were screened, and we should therefore reconsider any decisions based on the study,” explained Jonathan Shoag, MD, a urology resident at Weill Cornell Medical Center, and first author of the study.

In contrast, the European Randomized Study of Screening for Prostate Cancer found PSA screening correlated with a significant reduction in prostate cancer mortality over time.

Reference

1. Shoag JE, Mittal S, Hu JC. Reevaluating PSA testing rates in the PLCO Trial [published online ahead of print May 5, 2016]. N Engl J Med. doi:10.1056/NEJMc15151.