Minimum 6 mm core length is strongly predictive for the presence of glandular tissue in transrectal prostate biopsy.

INTRODUCTION: Prostate biopsy guidelines recommend that a prostate biopsy not containing glandular prostate tissue should be reported as inadequate. In the literature, there is a lack of any study that addresses the relationship between the length of biopsy cores and the absence of glandular prostate tissue. In this study, we aimed to determine whether a relationship exists between these parameters.
MATERIALS AND METHODS: We retrospectively evaluated 1,712 consecutive initial transrectal 12-core prostate biopsies. Individual cores were histologically categorized as glandular (benign or malignant) and non-glandular (rectal mucosa, periprostatic adipose tissue, prostatic or periprostatic fibromuscular tissue). Total number of evaluable cores ≤9, highly fragmented, incorrectly numbered or dried biopsies, patients with 5-α reductase inhibitory treatment were excluded.
RESULTS: We analyzed remaining 1,584 patients; 41.7 % had adenocarcinoma. A total of 19,144 cores were sampled. Non-glandular cores were found significantly shorter than glandular cores (p < 0.0001). The percentages of non-glandular cores were significantly higher at the base, apex and lateral biopsy sites (p < 0.0001). We found a 6-mm cutoff value for accurate prediction of glandular sampling with 80.2 % sensitivity and 78.7 % specificity. The risk of non-glandular sampling increased 15-fold in cores ≤6 mm (OR 14.91, 95% CI 13.20-16.83, p < 0.0001).
CONCLUSIONS: Non-glandular sampling was directly associated with shorter core lengths. They were found significantly higher at the base, apex and lateral localizations. We found a 6-mm cutoff value for the prediction of non-glandular samples before the histologic evaluation. Below this value, the risk of non-glandular sampling increased 15-fold. We suggest it for prompt additional sampling during biopsy procedure.