Detection of Prostate Cancer via Biopsy in the Medicare-SEER Population During the PSA Era

BACKGROUND: Despite the considerable attention given to the prostate-specific antigen (PSA) as a screening test for prostate cancer, it is needle biopsy--and not the PSA test result--that actually establishes the diagnosis of prostate cancer. We sought national estimates on the proportion of men found to have prostate cancer after a needle biopsy of the prostate and the risk of subsequent biopsies among those not found to have prostate cancer. METHODS: We linked Medicare claims data to Surveillance, Epidemiology, and End Results (SEER) data to analyze outcomes after 10,429 needle biopsies performed in 1993 through 2001 in 8273 men aged 65 years and older enrolled in Medicare Part B who resided in a SEER area. We determined the proportion of needle biopsies that were followed by a diagnosis of prostate cancer, the cumulative risk of prostate cancer following multiple biopsies, and the risk of subsequent biopsy among men not found to have prostate cancer in the previous biopsy. All statistical tests were two-sided. RESULTS: The overall proportion of needle biopsies found to contain prostate cancer was 32% (95% confidence interval CI = 31% to 33%). The yield increased with age (26% for men aged 65-69 years, 31% for men aged 70-74 years, 35% for men aged 75-79 years, and 41% for men aged 80 years and older; P(trend)<.001). The cumulative risk of prostate cancer diagnosis increased with repeated biopsy, with 50% of men receiving a prostate cancer diagnosis after two biopsies, 62% after three biopsies, and 68% after four biopsies. Among men whose first recorded biopsy did not detect prostate cancer, the risk of having a subsequent biopsy was 11.6% (95% CI = 11% to 12%) at 1 year and 38% (95% CI = 36% to 40%) at 5 years. CONCLUSIONS: About one-third of prostate biopsies identified prostate cancer in this population. Men not found to have prostate cancer on a first biopsy frequently undergo repeat biopsies, which raise the cumulative risk of prostate cancer diagnosis.