Prognostic Significance of Lymphatic, Venous and Perineural Invasion After Neoadjuvant Chemotherapy in Patients with Gastric Adenocarcinoma.

BACKGROUND: The significance of perineural (PNI), lymphatic (LI) and venous invasion (VI) in gastric cancer patients who have received neoadjuvant chemotherapy is unclear. The aim of this study is to determine the incidence and prognostic significance of LI, VI and PNI in these patients. PATIENTS AND METHODS: Consecutive patients treated with neoadjuvant chemotherapy followed by gastrectomy with D2 lymphadenectomy were reviewed. Presence of LI, VI and PNI was recorded and correlated with clinical outcomes. RESULTS: A total of 243 patients underwent gastrectomy after neoadjuvant therapy for gastric adenocarcinoma. LI was identified in 129 (53%), VI in 107 (44%) and PNI in 116 (48%) of patients. Presence of LI (HR, 2.95, CI 1.91-4.56), VI (HR, 2.66, CI 1.78-3.98) and PNI (HR, 3.85, CI 2.49-5.95) was associated with poorer survival (all p < 0.001). Multivariable analysis revealed that ypT stage (HR, 1.35, CI 1.05-1.74), ypN stage (HR, 1.53, CI 1.28-1.83) and PNI (HR, 2.11, CI 1.31-3.42) were independent predictors of survival. CONCLUSIONS: LI, VI and PNI are associated with poorer survival, with PNI having prognostic significance independent of lymph node status. These factors may be useful for further prognostication, in particular when multiple factors are present, and appear especially useful for prognostic stratification in patients with no nodal involvement.