Follow-up outcomes of endoscopic resection for early gastric cancer with undifferentiated histology

Background: The application of endoscopic resection (ER) for undifferentiated-type early gastric cancer (UD-EGC) remains controversial. The aim was to examine long-term outcomes of ER for UD-EGC. Furthermore, we investigated whether long-term outcomes of ER differed between poorly differentiated adenocarcinoma (PD) and signet ring cell carcinoma (SRC). Methods: From 2001 to 2011, 209 lesions in 209 patients with UD-EGC (82 PD; 127 SRC) were treated by ER. We retrospectively assessed the clinical outcomes of ER in 209 patients. The survival rate and disease-free survival rates after ER were evaluated as long-term outcomes. Results: The en bloc resection and curative resection (CR) rates were 91.4 and 55.0 %, respectively. The en bloc and CR rates in PD were 90.2 and 45.1 %, whereas those in SRC were 92.1 and 61.4 %. For patients with PD who underwent non-curative resections, 51.1 % were vertical-cut end-positive and for those with SRC, 63.3 % were lateral-cut end-positive, a statistically significant difference. In those patients where CR was achieved, no case of local recurrence or distant metastasis was observed during the follow-up period (32.7 ± 22.2 months). The 3- and 5-year survival rates were 99.0 and 98.6 %, with no significant difference between CR patients with SRC and PD. Conclusions: ER may yield good long-term outcomes for UD-EGC if CR is achieved, with no difference between PD and SRC. However, to increase the current CR rate of ER, stricter criteria for performing ER in UD-EGC may be required.