Objectives: To examine the significance of perineural invasion (PNI) in predicting pathologic findings in patients treated by radical prostatectomy, because a recent study concluded that PNI on needle biopsy has no independent predictive value.
Methods: Between 1993 and 1998, radical prostatectomy was performed in 319 consecutive patients. Prostate needle biopsies were reviewed in all cases. We compared PNI with other preoperative parameters, including digital rectal examination, PSA, and biopsy Gleason score, for the ability to predict tumor stage. Clinical records and pathologic findings were reviewed for all cases. Tumor stage was defined as either pT2 (organ confined) or pT3 (extraprostatic extension and/or seminal vesicle invasion).
Results: The median age was 61.4 years (range 40 to 75.6). Seventy-two percent of the 95 men with nonpalpable disease and 67% of the 224 men with palpable disease had organ-confined prostate cancer on final pathologic staging. Of 205 men with a Gleason score on biopsy of 6 or less, 159 (78%) had organ-confined disease compared with 59 (52%) of 114 with a Gleason score of 7 to 9 (P <0.001, chi-square test). PNI was identified in 77 (24%) of 319 patients, with 83% specificity and 40% sensitivity for Stage pT3 disease (odds ratio 3.49). Of men with pT3 disease on final pathologic staging, 18%, 27%, and 56% had preoperative PSA levels of 0 to 4, more than 4 to 10, and greater than 10 ng/mL, respectively (P <0.001, Mantel-Haenszel chi-square test). On multivariate analysis, PNI (P = 0.0031), PSA (P = 0.0004), and Gleason score (P = 0.0003) independently predicted stage (pT3 disease).
Conclusions: PNI is an important preoperative predictor of pathologic stage and should be reported when adenocarcinoma is diagnosed on prostate needle biopsies.