Causes of Death and Prognostic Factors in Patients with Superficial Esophageal Cancer Curatively Treated by Endoscopic Therapy: A Multicenter Cohort Study

<b>Background</b>: Endoscopic resection has become a standard curative treatment for superficial esophageal cancer. However, limited data are available regarding long-term outcomes and causes of death after curative endoscopic treatment, particularly deaths unrelated to the primary esophageal cancer. This study aimed to clarify post-treatment prognosis and to identify factors associated with mortality in patients with superficial esophageal cancer who underwent curative endoscopic resection. <b>Methods</b>: We conducted a multicenter cohort study in Japan to evaluate survival outcomes, causes of death, and prognostic factors in patients with superficial esophageal cancer who achieved curative resection by endoscopic treatment. Patients were stratified according to endoscopic treatment indication categories (absolute, relative, and beyond indication). Five-year overall survival and disease-specific survival were analyzed, along with risk factors for all-cause and cause-specific mortality. <b>Results</b>: No disease-specific deaths were observed in patients with absolute or relative indication lesions, whereas the disease-specific 5-year survival rate was 81% in patients with beyond-indication lesions. When overall mortality, including deaths from other diseases and other malignancies, was evaluated, the 5-year survival rates were 92% for absolute indication cases, 85% for relative indication cases, and 69% for beyond-indication cases. Multivariate analysis identified low body mass index (BMI) and advanced age as independent risk factors for mortality. Notably, low BMI was significantly associated with non-cancer-related death. <b>Conclusions</b>: Even among patients who achieve curative endoscopic treatment for superficial esophageal cancer, long-term survival is limited by deaths from other malignancies and non-cancer-related causes. Low BMI represents a clinically important prognostic factor, underscoring the need for comprehensive post-treatment surveillance and supportive care beyond cancer control.