P-0041 The Prognostic Significance of Perineural Invasion in Patients of Gastric Cancer

Abstract

IntroductionPerineural invasion (PNI) is the process of neoplastic invasion of nerves and is an under-recognized route of metastatic spread. Data from a large retrospective research suggest that PNI could function as an independent prognostic factor of outcomes in colorectal cancer (CRC) and PNI status should be considered in primary CRC specimens for therapy stratification. In this study we try to evaluate the prognostic significance of PNI in gastric cancer patients. MethodsThis study included gastric cancer patients who had undergone curative gastrectomy in our institution from January 2000 to December 2006. Pathological sections were stained with hematoxylin and eosin. Tumors were re-reviewed for PNI by a pathologist blinded to the patients' outcomes. PNI was assessed as positive when cancer cells in close proximity to nerve and involving at least 33% of its circumference or tumor cells within any of the 3 layers of the nerve sheath. The relationship between PNI positivity and other clinicopathological factors were analyzed using Chi-square test. Survival analysis and curves were established according to the Kaplan–Meier method and compared by the log-rank test. Multivariate analysis to assess the role of PNI and other clinicopathological features as prognostic factors were performed by the Cox regression analysis. ResultsPNI was positive in 121 of the 292 patients (41.44%). pTNM stage, tumor size, tumor differentiation, Borrmann classification and blood vessel invasion were closely associated with the presence of PNI. However, PNI was not related to age, sex, tumor location and resection type. The 5-year overall survival rate was 41.3% for PNI-positive tumors versus 77.8% for PNI-negative tumors (P<0.05). In patients with negative-lymph node, the 5-year overall survival rate was 68.8% for PNI-positive ones versus 96.5% for PNI-negative ones (P<0.05). Univariate analysis showed that overall survival was affected by many factors including perineural invasion. However, on multivariate analysis, PNI was not indicated as an independent prognostic factor for overall survival. ConclusionFor the whole group of patients and the node-negative patients, the overall survival of PNI positive patients was significantly shorter than that of PNI negative patients. PNI is an indicator of cancer aggressiveness. However, multivariate analysis did not show PNI was an independent prognostic factor for gastric cancer patients with curative gastrectomy. [Display omitted]