Core length in prostate biopsy: size matters

The diagnostic yield of prostate biopsy is limited. Increasing the number of cores enhances the cancer detection rate by sampling additional sites and obtaining more tissue. An alternative way to inspect more tissue would be to obtain longer cores. However, the impact of biopsy core length on cancer detection rate is an undervalued topic. We assessed the role of biopsy core length in prostate biopsy and determined the minimal tissue length to serve as quality assurance.

We retrospectively analyzed the records of 331 patients who underwent transrectal ultrasound guided initial prostate biopsy with 12 to 18 cores. The biopsy procedure and pathological evaluation were standardized. Core length was compared in patients with vs without cancer. Statistical analysis was done to determine a minimally acceptable cutoff for biopsy length.

We analyzed data on 245 patients. The overall cancer detection rate was 30.2%. Mean core length in patients with vs without cancer was 12.3±2.6 vs 11.4±2.4 mm (p=0.015). Thus, core length was significantly longer in patients with cancer. Core length greater than 11.9 mm was associated with an increased prostate cancer detection rate (OR 2.57, 95% 1.46-4.52). The cancer detection rate for cores less vs greater than 11.9 mm was 23% vs 39%.

Needle core length is an important morphometric parameter of transrectal prostate biopsy that directly influences the cancer detection rate. Results suggest a core length of greater than 11.9 mm as a cutoff for quality assurance.