Quantification of extraprostatic perineural spread and its prognostic value in pT3a pN0 M0 R0 prostate cancer patients

Abstract

The prognostic relevance of the amount of extraprostatic cancer spread in nerves in prostate cancer patients is not well established. Eighty-eight patients were included in our study with pT3a pN0 M0 R0 prostate cancer treated with retropubic prostatectomy. Eighty-seven of them showed perineural invasion, 54 were confined to the prostate, 33 showed cancer spread in extraprostatic nerves, which was quantified by counting each transverse section of nerves infiltrated by cancer in totally embedded specimens. Biochemical relapse was established by serum PSA levels of ≥0.2 ng/ml as well as PSA ≥ 0.4 ng/ml and higher according to the EAU guidelines. Extraprostatic but not intraprostatic perineural infiltration was significantly more often found in tumors of higher Gleason score. Intraprostatic number of infiltrated nerves (NIN) correlated with extraprostatic NIN. There was no association between extraprostatic or intraprostatic NIN and Gleason score, lymphatic, or blood vessel invasion. Extraprostatic neural infiltration in ≤10 nerves extended relapse free survival in univariate analysis for PSA 0.2 and 0.4 ng/ml (P = 0.002 and P < 0.000001, respectively) and remained significant in multivariate analysis for PSA 0.4 ng/ml (P = 0.039). High amount of extraprostatic NIN correlates with tumor progression and seems to be an independent prognostic parameter.