Long-term outcomes of endoscopic submucosal dissection in comparison to surgery in undifferentiated-type intramucosal gastric cancer using propensity score analysis.

BACKGROUND: The treatment of intramucosal early gastric cancer with undifferentiated-type histologies (UD-EGCs) using endoscopic submucosal dissection (ESD) is controversial. This study aimed to compare the clinical and oncologic long-term outcomes of ESD and surgery for UD-EGCs.

METHODS: A prospectively collected database of patients who underwent ESD or surgery between January 2006 and December 2012 was established. Patients who diagnosed with UD-EGC and satisfied the expanded indications of ESD were included. Clinical data from 111 patients treated with ESD and 382 patients underwent surgery were analyzed, and 1-1 propensity score-matched 81 pairs of patients were also compared.

RESULTS: In both groups, two-thirds of the UD-EGCs had signet ring cell (SRC)-type histology and about 90% of UD-EGCs were flat or depressed types. The mean size of tumors was smaller in ESD group (9.7 vs. 13.2 mm; P < 0.001). After propensity score-matched, case-matching covariates were not significantly different between the groups. Disease-free survival (DFS) was significantly shorter in the ESD group, but overall survival (OS) was not different between the two groups both in overall comparison (DFS; P < 0.001 and OS; P = 0.078) and propensity score-matched analysis (DFS; P < 0.001 and OS; P = 0.850). According to histologic type, OS of SRC histology was not different between the group, both in overall comparison and propensity score-matched analysis (P = 0.286 and P = 0.210). On the other hands, OS of poorly differentiated adenocarcinoma was significantly shorter in ESD group in overall comparison (P = 0.007), but was not as so in propensity score-matched analysis (P = 0.088).

CONCLUSIONS: ESD might be a complementary option for the treatment of UD-EGCs, especially in those with SRC-type histology based on strict expanded indications. Nonetheless, close endoscopic surveillance is required because of a high incidence of intragastric recurrence.