Sa1587 Long-Term Outcomes of Endoscopic Submucosal Dissection for Undifferentiated-Type Early Gastric Cancer

Abstract

undifferentiated-EGC (UD-EGC) remains controversial. The long-term clinical outcomes of the procedure have not yet been fully investigated. The aim of this study was to elucidate long term-outcomes of ER for UD-EGC. Furthermore, we investigated whether long-term outcomes of ER are different between poorly differentiated and signet ring cell carcinoma in UD-EGC. Methods: From January 2001 to December 2011, 209 lesions in 209 patients with UD-EGC (82 poorly differentiated adenocarcinoma (PD); 127 signet ring cell carcinoma (SRC)) were treated by ER at Severance and Gangnam Severance Hospital. We assessed the clinical outcomes of ER in 209 patients who underwent ER for the first time. The survival rate and disease free survival rates after ER were evaluated as the longterm outcomes. Results: The en bloc resection and curative resection (CR) rates were 91.4% (191/209) and 55.0% (115/209), respectively. The en bloc and CR rates in PD were 90.2% (74/82) and 45.1% (37/82), whereas those in SRC were 92.1% (117/127) and 61.4% (78/127). For patients with PD who underwent noncurative resection, 51.1% (23/45) were vertical margin positive and for those with SRC, 63.3% (31/49) were lateral margin positive with statistical significance (P 0.002). In those patients CR was completed, no cases of local recurrence and of distant metastasis were observed during the follow-up period (32.7 22.2, 3-97 month). 5 cases (4.3%, 5/115) of metachronous lesions were detected after ER without significant differences between CR patients with SRC and PD. The 3and 5-year survival rates were 99.0% and 98.6 without significant differences between CR patients with SRC and PD. Conclusions: ER may yield good long-term outcomes for UD-EGC if histologically CR is achieved without differences between PD and SRC. However, in order to increase the current CR rate of ER, stricter criteria for performing ER in UD-EGC may be required.