Risk factors associated with perineural invasion in prostate cancer

Objectives: The prognostic importance of perineural invasion (PNI) in prostate cancer (PC) has been postulated by some authors. Few studies have investigated the risk factors associated with PNI. The aim of this study was to identify factors associated with PNI in PC. Patients and methods: The study group of 113 patients diagnosed with PC during the period 2005–2010 consisted of 66 who underwent radical prostatectomy (RP) and 66 who did not. Each group was further divided into those with and without PNI. The association between clinicopathological parameters and PNI in prostate biopsy (Pbx) and RP specimens was investigated using t-test and logistic regression analysis. Discordance in PNI prevalence and PNI up-migration between Pbx and RP specimens were also studied. Results: In patients who did not undergo RP, Pbx Gleason score (GS)≥7 was a significant predictor for the presence of PNI. In patients who underwent RP, Pbx GS > 7 increased the risk of PNI in Pbx and RP samples, while a high RP GS predicted PNI in the RP specimen. The discordance rate for PNI in Pbx and RP specimens was 27.3%. Up-migration to a PNI positive cancer between Pbx and RP specimens was seen in 45.5% of cases and RP GS was the only factor associated with PNI up-migration. Conclusion: The association of PNI with a high GS and the high rate of discordance between Pbx and RP specimens indicate that in patients with a high GS on Pbx, the pathologist should look more carefully for PNI, and the surgeon should be aware of sampling errors and the unreliability of Pbx specimens in detecting PNI.