Perineural Invasion Independent Prognostic Factors in Patients with Gastric Cancer Undergoing Curative Resection

Objective: The prognostic significance of perineural invasion (PNI) in gastric cancer has been previouslyinvestigated but not clearly clarified. The objective of our study was to investigate the role of PNI as prognosticfactor in patients undergoing curative surgical resection and without distant metastasis in comparison with otherclinicopathological factors.
Methods: Between 2001 and 2010, 287 cases of gastric adenocarcinoma underwentradical gastrectomy recorded in hospital based registries. PNI was assessed as positive when cancer cells wereseen in the perinerium or neural fascicles intramurally. Categorical and continuous variables were summarizedusing descriptive statistics and compared using chi-square and Mann-Whitney U tests, respectively. Cancer relatedsurvival rates were estimated by the Kaplan-Meier method.
Results: PNI was positive in 211 of 287 cancers (73%),with a positive relation to lymph node metastases and advanced stage (p=0.0001, p=0.0001, respectively), muralinvasion, and lymphatic and blood vessel invasion (p=0.0001, p=0.0001, respectively). The median survival ofthe PNI positive patients was significantly shorter than that of their PNI negative counterparts (24.1 versus 38.2months, p=0.008). In the multivariate analysis, we detected PNI was an independent prognostic factor (p=0.025,HR=1.21, 95% CL 1.08-2.3) along with classical clinicopathological variables such as lymph node involvement(p=0.001), pT stage (p=0.03), and LVI (p=0.017), but not age, gender, tumour localization, stage, histologic type,and surgery procedure.
Conclusions: PNI positivity in gastric cancers was related mural invasion, lymph nodeinvolvement, advanced stage and lymphatic and venous blood vessels. The presence of PNI appeared as anindependent prognostic factor on survival on multivariate analysis, not influenced by tumor stage, lymph nodemetastases and other classical factors.