The effect of perineural invasion on overall survival in patients with gastric carcinoma

Aims The availability of different treatment options for gastric carcinoma has reopened the question of correct definition of high-risk categories, which may help in identifying patients with high risk for poor prognosis who would benefit more from adjuvant therapy after operation. Perineural invasion (PNI) seems to provide useful information for management. Therefore, we examined the effect of PNI on overall survival (OS) in patients with gastric carcinoma and the association between PNI and other clinical and pathological factors. Patients and Methods A total of 1,632 patients with gastric carcinoma from 2000 to 2005 were analyzed retrospectively. Paraffin sections of surgical specimens from all patients who underwent gastric resection were stained with laminin. If carcinoma cells infiltrated into the perineurium or neural fascicles, PNI was assessed as positive. Survival analysis was done in 1,372 patients with T1-T4 tumors who underwent curative resection. Result PNI was positive in 518 of the 1,632 patients (31.7%). The size of tumors, T stage, differentiation of tumor, and clinical stage were significantly related to PNI positivity. The proportion of large tumors was significantly higher in PNI-positive patients than in PNI-negative patients (P < 0.01). As the depth of gastric mural invasion or clinical stage increased, the positive rate of PNI also increased. The OS of the PNI-positive patients was significantly shorter than that of the PNI-negative patients in the univariate analysis (P < 0.01). At multivariate Cox proportional hazards model of OS analysis, the positivity of PNI appeared to be an independent prognostic factor for OS (hazards ratio [HR]=3.23, 95%CI=2.6-8.11, P < 0.01), which was also influenced by tumor differentiation, T stage, and clinical stage (P < 0.01). Conclusion Our results suggested that the incidence of PNI was high in gastric carcinoma and that it corresponded to the progression of disease. It could provide additional information for identifying patients who are at high risk for poor prognosis. PNI can be a candidate for a new kind of prognostic parameters.