PSA testing: Medical studies' "incongruent results" add to the controversy

http://www.ncbi.nlm.nih.gov/pubmed/21717898

Oncology (Williston Park). 2011 May;25(6):452-60, 463.
Screening for prostate cancer with PSA testing: current status and future directions.
Croswell JM, Kramer BS, Crawford ED.
Source
Agency for Healthcare Research and Quality, Rockville, Maryland 20850, USA. jennifer.croswell@ahrq.hhs.gov

Abstract
The ultimate utility of the serum prostate specific antigen (PSA) assay as a screening test for reducing prostate cancer mortality has been an area of intense controversy since its introduction. PSA testing was not initially envisioned as a screening tool, but as a way to evaluate treatment responses in men with prostate cancer. Far in advance of evidence from randomized trials, the rapid and widespread uptake of PSA screening into US practice was initially driven by the intuitively logical assumption that the earlier one detects a malignancy, the more likely treatment is to be curative while minimizing associated harms. However, a growing body of observational evidence began to point to a substantial burden of associated overdiagnosis and overtreatment triggered by PSA testing. The interim results of several randomized clinical trials specifically designed to evaluate the impact of PSA testing on prostate cancer mortality have recently become available, but their incongruent results seem to have added fuel to the debate. This article presents a review of the literature on screening for prostate cancer with PSA testing; we include a detailed discussion of potential explanations for the contradictory results of the two largest randomized trials as well as reflections on the future of prostate cancer screening.