Prognostic effect of perineural invasion in successive years in patients with locally advanced gastric cancer

The present study evaluates the prognostic significance of perineural invasion (PNI) on 2-year, 5-year, and overall survival in patients undergoing gastrectomy and D2 lymphadenectomy due to locally advanced gastric cancer.Included in the study were 231 patients who underwent surgery between November 2006 and October 2018 due to stage 1B and over locally advanced gastric cancer, whose records were reviewed retrospectively.The variables in the presence or absence of PNI were compared between the two groups with a Chi-square test, a Fisher's exact test, a likelihood ratio, and a Mann-Whitney U test. Overall survival data were evaluated with a Kaplan-Meier test. Prognostic factors were evaluated with a stepwise Cox regression analysis.PNI was identified in 167 (72.3%) of the patients. The 2-year, 5-year, and overall survival rates at the end of the follow-up period were 85.9%, 70.3%, and 64.1% in those without PNI, and 52.7%, 38.3%, and 36.5% in those with PNI, respectively. In a multivariate analysis, PNI appeared to be a significant prognostic factor for 2-year survival (P = 0.04) but had no effect on 5-year and overall survival.Survival was shorter in patients with PNI than in patients without PNI, and PNI had no effect on overall survival, although it was found to be of prognostic significance for 2-year survival.