SPP1 and chronic gastritis: In this study, we found that the effects of smoking and drinking on OPN expression in patients with mild SG were not replicated in patients with AG or GC, so we speculate that the influences of smoking and drinking on GC risk may lie principally in the process of transition from SG to AG, rather than the subsequent transition from AG to GC, and OPN may play an important role in the process of chronic gastritis to atrophy, despite the lack of published evidence.