Long-term outcomes of endoscopic submucosal dissection for undifferentiated type early gastric cancer over 2 cm with R0 resection.

Background: Endoscopic submucosal dissection (ESD) for over 2 cm in size undifferentiated type (UD type) early gastric cancer (EGC) confined to the mucosa is not only challenging, but also long-term outcomes are not well known.

Aim: To evaluate the long-term outcomes of ESD done for UD type EGCs confined to the mucosa over 2 cm in size and compare the results with those where the lesions were less than 2 cm.

Methods: 143 patients with UD type EGC confirmed on histology after ESD at a tertiary hospital were reviewed. Cases with synchronous and metachronous lesions and a case with emergency surgery after ESD were excluded. A total of 137 cases were enrolled. 79 cases who underwent R0 resection were divided into 2 cm or less (group A) and over 2 cm (group B) in size.

Results: Among 79 patients who underwent R0 resection, the number in group A and B were 51 and 28, respectively. The mean follow-up period (SD) was 79.71 ± 45.42 months. There was a local recurrence in group A (1/51, 2%) and group B (1/28, 3.6%) respectively. This patient in group A underwent surgery while the patient in group B underwent repeated ESD with no further recurrences in both patients. There was no regional lymph node metastasis, distant metastasis, and deaths in both groups. With R0 resection strategy for ESD on lesions over 2 cm, 20.4% (28/137) of patients were able to avoid surgery compared with expanded indication.

Conclusion: If R0 resection is achieved by ESD, UD type EGCs over 2 cm also showed good and similar clinical outcomes as compared to lesions less than 2 cm when followed for over 5 years. With R0 resection strategy, several patients can avoid surgery.