Prognostic significance of perineural invasion in patients with gastric cancer who underwent curative resection

Background: The prognostic significance of perineural invasion (PNI) in gastric cancer has been previously investigated in a few studies, but had not reached a consensus. The aim of this study was to determine the prognostic value of PNI in patients with gastric cancer who underwent curative resection. Materials and Methods: We retrospectively analyzed 238 patients who had undergone curative gastrectomy. Paraffin sections of surgical specimens from all patients were stained with hematoxylin and eosin. PNI was defined when carcinoma cells infiltrated into the perineurium or neural fascicles. PNI and the other prognostic factors were evaluated by univariate and multivariate analysis. Results: PNI was detected as positive in 180 of the 238 patients (75.6%). pT stage, tumor size, lymph node metastasis, clinical stage, tumor differentiation, Borrmann classification, histological type, lymphatic vessel invasion, and blood vessel invasion were closely associated with the presence of PNI. The PNI-positive tumors had significantly larger size and more lymph node metastasis than the PNI-negative tumors (P =.001 and P <.001, respectively). The median survival of the PNI-positive patients was significantly worse than that of the PNI-negative patients (28.1 vs. 64.9 months, P =.001). Multivariate analysis indicated that the positivity of PNI was an independent prognostic factor (P =.02, hazard ratio [HR]: 2.75; 95% confidence interval [95% CI]:1.12-3.13) as were classical clinicopathological features. Conclusion: Our results showed that the frequency of PNI was high in patients with gastric cancer who underwent curative gastrectomy and the proportion of PNI positivity increased with progression and clinical stage of disease. PNI may be useful in detecting patients who had poor prognosis after curative resection in gastric cancer.