Prostate cancer polar localization on core biopsy predicts pathologic stage.

INTRODUCTION: This study investigated the polar sub-localization of prostate cancer on needle core biopsy ('polar' defined as tumor = 1 mm from the tissue polar edge) as a predictor of extraprostatic extension.

MATERIALS AND METHODS: Histologic sections from 58 patients who underwent preoperative prostate biopsy and radical prostatectomy at the University of Kentucky from 2006 to 2013 were evaluated. Patients were retrospectively case matched based on pathologic stage (pT2 versus pT3/4) using biopsy Gleason grade and prostate-specific antigen. Histologic sections of needle core biopsies were analyzed for polar involvement. The location of polar involvement was correlated to the presence of extraprostatic extension on final prostatectomy pathology.

RESULTS: Average percentage of total polar cores was predictive of extraprostatic extension on final prostatectomy, particularly in the prostatic apex and base (p = 0.029 and 0.006, respectively). Higher grade tumors were identified at the pole in the high stage cohort (p = 0.032). Total percent polar involvement had the greatest sensitivity and specificity for predicting extraprostatic extension when directly compared to previously described histologic parameters (percent greatest involvement of a single core, length of greatest involvement of a single core, presence of perineural invasion, presence of bilateral gland involvement, and percent total positive core involvement). The location of polar involvement on needle core biopsy was also predictive of the precise location of extraprostatic extension on final prostatectomy pathology (Chi-square p < .001, negative predictive value > 70% in all prostate sextants).

CONCLUSIONS: These data suggest the use of biopsy polar core involvement as a valuable histologic predictor of increased pathologic stage.