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BACKGROUND: A systematic repeat biopsy is recommended for men starting on active surveillance for prostate cancer, but the optimal number and distribution of cores are unknown.

OBJECTIVE: To evaluate an extensive repeat transrectal biopsy with anterior sampling in men starting on active surveillance.

DESIGN, SETTING, AND PARTICIPANTS: Randomised multicentre trial. From 2012 to 2016, 340 Swedish men, aged 40-75yr, with recently diagnosed low-volume Gleason grade group 1 prostate cancer were included.

INTERVENTION: Either an extensive transrectal biopsy with anterior sampling (median 19 cores) or a standard transrectal biopsy (median 12 cores).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Primary outcome measure: Gleason grade group ≥2 cancer.

SECONDARY OUTCOMES: Cancer in anteriorly directed biopsy cores and postbiopsy infection. Nonparametric statistical tests were applied.

RESULTS AND LIMITATIONS: Gleason grade group ≥2 cancer was detected in 16% of 156 men who had an extensive biopsy and in 10% of 164 men who had a standard biopsy, a 5.7% difference (95% confidence interval [CI]-0.2% to 13%, p=0.09). There was a strong linear association between prostate-specific antigen (PSA) density and cancer in the anteriorly directed biopsy cores. The odds ratios for cancer in the anteriorly directed cores were for any cancer 2.2 (95% CI 1.3-3.9, p=0.004) and for Gleason grade group ≥2 cancer 2.3 (95% CI 1.2-4.4, p=0.015) per 0.1-ng/ml/cm³ increments. Postbiopsy infections were equally common in the two groups. A limitation is that magnetic resonance imaging was not used.

CONCLUSIONS: The trial did not support general use of the extensive transrectal repeat biopsy template, but cancer in the anteriorly directed cores was common, particularly in men with high PSA density. The higher the PSA density, the stronger the reason to include anterior sampling at a systematic repeat biopsy.

PATIENT SUMMARY: This trial compared two different templates for transrectal prostate biopsy in men starting on active surveillance for low-risk prostate cancer. Cancer was often found in the front part of the prostate, which is not sampled on a standard prostate biopsy.