Case Control Studies in Evaluating Prostate Cancer Screening: An Overview

ObjectivesOngoing randomized controlled screening trials for prostate cancer have not shown a beneficial effect on prostate cancer mortality reduction yet. A large number of observational (non-randomized) studies on prostate cancer screening have been published with contradictory outcome. This paper reviews the current case-control studies.MethodsSeven case-control studies of screening for prostate cancer were identified in a PubMed search, published from 1991 onwards, all conducted in North America. The screening test was either digital rectal examination (DRE) alone or in combination with PSA.ResultsOne DRE case-control study, found a significant preventive effect, whereas two others showed no effect of DRE screening on prostate cancer mortality nor on the occurrence of metastatic disease. Conflicting results were also observed in the studies assessing the effect of PSA/DRE. Only one study showed a significant 27% mortality reduction in the White male cohort, but found no effects in Blacks. The most recent study showed that screening with PSA/DRE was not protective in reducing prostate cancer mortality.ConclusionsOur review of the case-control studies does not indicate a benefit of prostate cancer screening. An answer has to come from the ERSPC trial, in Europe, and the PLCO trial, in the US, of which the outcomes are expected in 2007–2010.