Prediction of extraprostatic extension of prostate cancer based on needle biopsy findings: Perineural invasion lacks significance on multivariate analysis

Extraprostatic extension (EPE) and seminal vesicle invasion (SVI) are adverse prognostic factors in prostate cancer, and their prediction before prostatectomy would be useful. Perineural invasion in needle biopsy has been advocated as a marker of extraprostatic extension, but its independent value as a predictor of stage has not been established. We studied 349 previously untreated men with prostatic adenocarcinoma who underwent bilateral pelvic lymphadenectomy and radical retropubic prostatectomy. All patients were clinically free of metastases and had cancer that was diagnosed on needle biopsy. Five preoperative variables were collected: clinical stage (TNM staging system), serum prostate-specific antigen (PSA), Gleason score on needle biopsy, presence or absence of perineural invasion, and proportion of the biopsy involved by cancer. The subsequent prostatectomy specimens were completely embedded, and whole mount sections were used to evaluate four outcome staging variables: EPE (absent/present), EPE (absent/unilateral/bilateral), seminal vesicle invasion, and pathologic stage (TNM). On univariate analysis, each preoperative variable was significantly associated with each outcome variable except for a lack of association between clinical stage and SVI. Perineural invasion in the biopsy predicted EPE with a sensitivity of 51%, specificity of 70%, positive predictive value of 49%, and negative predictive value of 71%. On multivariate analysis (stepwise logistic regression), only preoperative PSA, proportion of the biopsy involved by cancer, and Gleason score were significant (p < 0.05); perineural invasion and clinical stage had no independent predictive value for any of the outcome variables. We conclude that the finding of perineural invasion in needle biopsy of prostatic carcinoma has no independent predictive value for the presence of extraprostatic extension, seminal vesicle involvement, or pathologic stage in the radical prostatectomy. Accordingly, we no longer routinely evaluate this finding in biopsy specimens.