Following gastrectomy, the remnant oxyntic mucosa is at increased risk of developing adenocarcinoma. Alkaline pancreaticoduodenal reflux, carcinogen production from intragastric bacterial overgrowth, denervation, and devascularization have been implicated in this malignant transformation. Recent reports have described a novel spasmolytic polypeptide (SP) expressing metaplastic lineage designated as SPEM. This lineage has been identified in the mucosa surrounding gastric adenocarcinomas, and SP staining has been observed in the cells of surface dysplasia and invasive malignancy. In this study we describe 19 cases of remnant gastric adenocarcinoma from Japan. In addition, we studied surveillance biopsies in 90 patients who underwent antrectomy for carcinoma. SPEM was identified in the mucosa surrounding 88% of the remnant cancers, as well as in 61% of the surveillance biopsies. In the malignant resections, 67% of the surface dysplasia displayed SP positive cells, and 25% revealed SP immunostaining within invasive malignant cells. These findings implicate SPEM as a potential precursor lesion of gastric adenocarcinoma.