ABSTRACT
Early detection and treatment decrease the mortality rate associated with gastric cancer (GC). However, the natural history of GC remains unclear. An 85-year-old woman was referred to our hospital for evaluation of a gastric tumor. Esophagogastroduodenoscopy identified a 6 mm, flat-elevated lesion at the lesser curvature of the antrum. A biopsy specimen showed a well-differentiated tubular adenocarcinoma. The depth of the lesion was estimated to be intramucosal. Although the lesion met the indications for endoscopic resection, periodic endoscopic follow-up was performed due to the patient's advanced age and comorbidities. The mucosal GC invaded into the submucosa 3 years later, and finally progressed to advanced cancer 5 years after the initial examination. The patient died of tumor hemorrhage 6.4 years after the initial examination. In this case, mucosal GC progressed to advanced GC, eventually leading to the patient's death from GC. Early and appropriate treatment is required to prevent GC-related death.