184. TREATMENT OUTCOMES OF ENDOSCOPIC SUBMUCOSAL DISSECTION FOR LONG-SEGMENT BARRETT’S ESOPHAGUS-DERIVED ESOPHAGEAL ADENOCARCINOMA

Abstract Background In Japan, ESD is generally used to resect localized areas of LSBE-derived esophageal adenocarcinoma(EAC), just as it is effectively employed for the more prevalent SSBE-derived EAC. However, as Barrett’s esophagus lengthens, cancer margins become less distinct, and metachronous EACs occur more frequently, making diagnosis and treatment more challenging. In Western countries, radiofrequency ablation is performed alongside endoscopic resection for LSBE eradication. In contrast, in Japan, ESD is performed even in such cases with precise margin assessment. However, there is limited data on ESD outcomes for LSBE-derived EAC. We aimed to clarify the treatment outcomes of LSBE-derived EAC. Methods We retrospectively analyzed 268 EAC cases (LSBE, 72 cases with 77 lesions; SSBE, 196 cases with 198 lesions) that underwent ESD at Cancer Institute Hospital, Mie University Hospital, and Kumamoto University Hospital between April 2006 and August 2024. Surveillance was performed for cases with low metastasis risk, defined as mucosal cancer or EAC with submucosal invasion ≤500 μm and ≤ 30 mm in size, both without lymphovascular invasion (LVI) or poorly differentiated components. Short-term outcomes included the R0 resection rate, while long-term outcomes included esophageal preservation survival and metachronous recurrence-free survival in surveillance cases, and overall survival in all cases. Results Of 268 cases, the median age was 67, and 87% were male. The median tumor size was 15 mm/10 mm, submucosal invasion was 26%/27%, and LVI was 16%/22%. The R0 resection rates were 79%/88%(p = 0.08) for LSBE/SSBE. The 5-year overall survival was 92%/88% (p = 0.83). Among surveillance cases (LSBE/SSBE;n = 55/153), metachronous EAC occurred in 7 LSBE cases and 1 SSBE case. Esophagectomy was performed in 4 LSBE cases: 2 for metachronous EACs, 1 each for local recurrence and extensive EAC. The 5-year rates of esophageal preservation and metachronous recurrence-free survival were 91%/100% (p < 0.01) and 82%/99% (p < 0.01) for LSBE/SSBE, respectively. Conclusion ESD for LSBE-derived EAC showed favorable outcomes, with high survival rates. However, LSBE cases sometimes failed to preserve the esophagus, while SSBE cases could maintain it, even after the successful ESD for the localized initial EAC in both groups. Further investigation of treatment strategies, including eradication approaches, is necessary to improve outcomes for LSBE-derived EAC.