Relationship between perineural tumor invasion on needle biopsy and radical prostatectomy capsular penetration in clinical stage B adenocarcinoma of the prostate.

We studied 302 needle biopsies for perineural invasion for sensitivity and specificity in predicting capsular penetration in subsequent radical prostatectomies. Perineural invasion was seen in 20% of needle biopsies, with a sensitivity of 27% and a specificity of 96% in predicting capsular penetration. By including tumor with a Gleason sum of 7 or greater or perineural invasion on needle biopsy as being predictive, sensitivity increased to 36% with a specificity of 94%. By restricting perineural invasion to cases with more than one nerve involved or a nerve involvement of a diameter 0.1 mm or greater, specificity increased to 97% and 99%, respectively, with sensitivity falling to 15% and 9%, respectively. Measuring perineural invasion on needle biopsy helps to identify capsular penetration and may help in planning nerve-sparing radical prostatectomy in the decision of whether to sacrifice part or all of the neurovascular bundle on the side of the biopsy.