Positive Prostate Biopsy Rate Consistently Increases with Age at the Same Prostate-Specific Antigen Level in Patients with Normal Digital Rectal Examination

Abstract

Objectives. To examine the relationship between positive prostate biopsy rates and age over the range of serum prostate-specific antigen (PSA) concentrations of 4 to 10 ng/mL. Methods. The rates for adenocarcinoma were calculated for prostate biopsy specimens received at UroCor Inc., Oklahoma City, Oklahoma between April 1995 and June 1997. The selection criteria were as follows: men between 50 and 79 years of age, normal digital rectal examination (DRE), prebiopsy PSA level between 4.01 and 10.0 ng/mL obtained within a 4-month period prior to receipt of biopsy, and no previous prostate biopsy. Five thousand six cases were selected out of 81,545 prostate biopsy specimens submitted by office-based urologists. The rates of positive prostate biopsies were stratified by age in decade increments and by PSA in increments of 1 ng/mL. The P values were calculated by the chi-square test. Results. The patient mean age was 65.8 years. An overall increase in the positive prostate biopsy rate for men between 50 and 79 years of age as serum PSA increases from 4.01 to 10.0 ng/mL ( P = 0.047) was found; however, this increase was less significant than the increase found in positive biopsy rates caused by age alone ( P <0.0001). Conclusions. Undetected prostate cancer appears to be a major cause of the increasing serum PSA seen with advancing age.