Prostate-specific antigen screening trials and prostate cancer deaths: the androgen deprivation connection

Abstract

Major clinical trials using prostate-specific antigen (PSA) as the screening test to detect localized early-stage prostate cancer and to attempt to change its natural history with early intervention have yielded conflicting interpretations. The US Prostate, Lung, Colorectal, and Ovarian (US PLCO) cancer screening trial concluded that PSA-based screening conferred no meaningful survival benefit, whereas the European Randomized Study of Screening for Prostate Cancer (ERSPC) and the GOTEBORG clinical trial (GOTEBORG) trials claimed statistically significant life-saving benefits. These divergent outcomes have not provided physicians with clarity on the best evidence-based treatment. To determine the extent to which these divergent outcomes are clinically meaningful, we evaluated these data and those of a long-term prospective cohort study in the context of the clinically documented harms of androgen deprivation therapy (ADT). We noted the unheralded fact that in both European trials far more patients received hormonal treatment in the control than the prostatectomy arm, whereas hormonal therapy in the US trial was balanced between arms. We examined this imbalance in ADT treatment and prostate cancer-related deaths in the contexts of contamination, stage migration, and attribution of cause of death, all of which impinge on data interpretation. The ERSPC and GOTEBORG data are compatible with the hypothesis that ADT treatment contributes differentially to an increase in prostate cancer deaths in control patients. If so, the claim of a reduction in prostate cancer deaths in the screened cohort requires reappraisal. The conventional interpretation that PSA screening and radical treatment intervention are the major contributors to the results of these two studies needs more rigorous scientific scrutiny, as does the role of ADT treatment of nonmetastatic disease.