Impact of High Altitude on Clinicopathological Features and Prognosis after R0 Resection for Gastric Cancer: A Population-Based Multicenter Study.

Geographic variation has an important role in both carcinogenesis and prognosis of gastric cancer (GC). High altitude is a special hypoxic environment that is also correlated with the occurrence of GC. Different onset features and prognoses of GC in high altitude with respect to plains are rarely reported and remain unknown. This multicenter study compared different clinicopathological characteristics and prognoses of patients with resected GC who were from locations of both high altitudes and plains in China. From December 2009 to December 2011, patients with resected GC were retrospectively recruited at four centers located at high altitudes and the plains. Clinicopathological data were analyzed to explore the differences between the two groups. The Cox proportional-hazards model was used to investigate the prognostic factors for GC and estimate the independent impact of altitude on long-term survival after adjusting for covariates. Noncardia GC, from a moderate to well tumor grade, was more common in patients from high altitudes. Moreover, a higher proportion of moderate to well and moderate tumor grade and younger age of onset was found in patients with noncardia GC coming from high altitudes. Different overall survival (OS) presented in noncardia GC rather than cardia GC, with 69.94% GC-related 3-yr OS in high altitude versus 75.23% in the plains. High altitude was confirmed as a significant prognostic factor for noncardia GC (the hazard ratio for high altitude vs. plains was 1:50, with a 95% confidence interval; 1.06-1.82, p = 0.018) through a multivariate Cox proportional-hazards model analysis. This prognostic value was independent of all other factors. High altitude has an important role in clinicopathological features and prognosis of GC. Improvements in GC diagnosis and management at high altitudes are urgently needed.