Clinical significance of the relative location of perineural cancer invasion on prostate biopsy: Detection within 1-mm of the core tip as an independent prognosticator.

Perineural invasion (PNI) detected on prostate biopsy is a recognized indicator of aggressive disease including extraprostatic extension. However, the clinical relevance of its relative location within the biopsy core remains poorly understood. We herein assessed corresponding radical prostatectomy findings and long-term oncologic outcomes in 180 prostate cancer patients exhibiting only a single focus of PNI on the entire systematic biopsy. PNI was located at <1-mm (n = 26; 14.4 %), ≥1 to <2-mm (n = 43; 23.9 %), ≥2 to <3-mm (n = 36; 20.0 %), ≥3 to <4-mm (n = 27; 15.0 %), ≥4 to <5-mm (n = 28; 15.6 %), or ≥5-mm (n = 20; 11.1 %) from the closest tip of the core. Univariate survival analysis in the dichotomized cohort based on the distance revealed significantly higher risks of biochemical recurrence (P < 0.001) and cancer-specific mortality (P = 0.042) in patients with PNI located <1-mm from the core tip than in those with PNI ≥1-mm. There were no significant differences in the clinicopathologic features examined, including total tumor length on biopsy or estimated tumor volume on prostatectomy, tumor grade on biopsy or prostatectomy, pT or pN category, and surgical margin status, between the <1-mm vs. ≥1-mm groups. In multivariable Cox regression analysis, PNI <1-mm from the tip (vs. ≥1-mm) showed significantly worse recurrence-free survival both before (hazard ratio 3.435, P < 0.001) and after (hazard ratio 3.228, P = 0.002) adjusting for prostatectomy factors. PNI detected within 1-mm of the biopsy core tip was thus found to independently predict a worse postoperative prognosis. This spatial detail of PNI on needle core biopsy may enhance the risk stratification of prostate cancer.