Perineural invasion as an independent predictor of biochemical recurrence in prostate cancer following radical prostatectomy or radiotherapy: a systematic review and meta-analysis

BACKGROUND Although numerous studies have shown that perineural invasion (PNI) is linked to prostate cancer (PCa) risk, the results have been inconsistent. This study aimed to explore the association between PNI and biochemical recurrence (BCR) in patients with PCa following radical prostatectomy (RP) or radiotherapy (RT). METHODS According to the PRISMA statement, we searched the PubMed, EMBASE, Chinese National Knowledge Infrastructure (CNKI) and Wan Fang databases from inception to May 2017. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) were extracted from eligible studies. Fixed or random effects model were used to calculate pooled HRs and 95% CIs according to heterogeneity. Publication bias was calculated by Begg's test. RESULTS Ultimately, 19 cohort studies that met the eligibility criteria and that involved 13,412 patients (82-2,316 per study) were included in this meta-analysis. The results showed that PNI was associated with higher BCR rates in patients with PCa after RP (HR=1.23, 95% CI: 1.11, 1.36, p<0.001) or RT (HR=1.22, 95% CI: 1.12, 1.34, p<0.001). No potential publication bias was found among the included studies in the RP group (p-Begg = 0.124) or the RT group (p-Begg = 0.081). CONCLUSIONS This study suggests that the presence of PNI by histopathology is associated with higher risk of BCR in PCa following RP or RT, and could serve as an independent prognostic factor in patients with PCa.