Yearly Prostate Specific Antigen and Digital Rectal Examination Fluctuations in a Screened Population

Abstract

Prostate biopsy is often recommended based on elevations in prostate-specific antigen (PSA) and/or abnormal digital rectal examination (DRE). We investigate the stability of a single positive test over the next 3 consecutive years. 2578 participants in a San Antonio screening cohort with two or more consecutive annual PSA and DRE tests were identified. Numbers of occurrences of an elevated PSA (≥ 2.5 ng/ml) followed by one or more non-elevated PSA results were compared with similar fluctuations of DRE from abnormal to normal. Among 2272 men who never had a biopsy performed during the study, in 23.3% of 744 incidences of an elevated PSA with one year of follow-up, the next PSA was not elevated, in 19.5% of 353 incidences of an elevated PSA with two years of follow-up, the next two consecutive PSAs were not elevated, and in 17.5% of 68 incidences of an elevated PSA with three years of follow-up, the next three consecutive PSAs were not elevated. Rates were similar but lower among 221 men with one or more negative biopsies during the study and 85 men who eventually developed prostate cancer during the study. In contrast, approximately 70% of abnormal DREs were normal the following year, even among prostate cancer cases, and in the majority of incidences, remained normal the next 2 to 3 consecutive years. Occurrences of reversed PSA cutpoint- or abnormal DRE-based decisions to biopsy one or more years after the initial test are not uncommon, suggesting repetition of these tests.