e15569 Background: When a tumor invades to the muscularis mucosa or submucosal layer (T1a-MM or T1b, in Japan), cSt I esophageal cancer(EC) has 10–50%. risk of lymph node metastasis (LNM). Surgery, though very invasive, is the standard radical therapy for the patients(pts.) with such stage EC. Endoscopic mucosal resection (EMR), which conserves the esophagus, is a minimally invasive and attractive therapeutic modality for such pts. However, the clinical outcomes of EMR for these pts. have been not fully elucidated. Methods: We conducted retrospective analysis of the clinical courses of 44 pts. who underwent EMR for newly diagnosed T1a-MM or T1bcN0M0 EC between 1994 and 2007at our hospital, and who could be followed up for at least 1 year. Statistical analysis was performed by the Kaplan-Meier methods and the Cox proportional hazard model. Results: Patients decided on the following treatments immediately after EMR based on informed consent and their general condition; 2 underwent surgery, one underwent prophylactic chemotherapy(CHT) and 41 selected follow-up without any additional therapy. Of the 41, 20 selected this course by choice, 12 because of severe concurrent disease; 2 because of poor performance status and 7 because of other multiple primary cancers (MPCs). Twelve pts. died; 2 were cause specific; (4.5%), 8 from MPCs and, 2 from unknown causes. Median age was 67 years old (range 53–80), and 5 were female. No critical comlications were noted. Median follow-up time was 1542days (375–3786). 5 developed LNM. One with prophylactic CHT, was followed by surgery, and another was followed by CHT, who showed cause specific deaths later. Other 3 pts. followed by chemoradiotherapy, did not show cause specific death. Overall and cause specific survival rates at 5 years were 67.3% and 91.8%, respectively. Multivariate analysis revealed that either severe concurrent disease or MPCs significanctly influenced survival (p=0.041, HR 5.437(95%CI 1.073–25.542)). 8 and 6 pts. developed metachronous EC and local recurrence, respectively. Apart from one, they could be retreated endoscopicaly. Conclusions: EMR is a very useful therapeutic modality for cSt I EC, not only for local control but also as a clinically sufficient treatment; especially in pts. with severe concurrent disease. No significant financial relationships to disclose.