Objectives
To compare the incidence of subsequent prostate cancer diagnosis and death following an initial non-malignant systematic transrectal ultrasonography (TRUS) biopsy with that in an age- and calendar-year matched population over a 20-year period.

Subjects and Methods
This population-based analysis compared a cohort of all men with initial non-malignant TRUS biopsy in Denmark between 1995 and 2016 (N = 37 231) with the Danish population matched by age and calendar year, obtained from the NORDCAN 9.1 database. Age- and calendar year-corrected standardized prostate cancer incidence (SIR) and prostate cancer-specific mortality ratios (SMRs) were calculated and heterogeneity among age groups was assessed with the Cochran's Q test.

Results
The median time to censoring was 11 years, and 4434 men were followed for more than 15 years. The corrected SIR was 5.2 (95% confidence interval [CI] 5.1–5.4) and the corrected SMR was 0.74 (95% CI 0.67–0.81). Estimates differed among age groups (P < 0.001 for both), with a higher SIR and SMR among younger men.

Conclusion
Men with non-malignant TRUS biopsy have a much higher incidence of prostate cancer but a risk of prostate cancer death below the population average. This underlines that the oncological risk of cancers missed in the initial TRUS biopsy is low. Accordingly, attempts to increase the sensitivity of initial biopsy are unjustified. Moreover, current follow-up after non-malignant biopsy is likely to be overaggressive, particularly in men over the age of 60 years.