Risk of recurrent gastric cancer after endoscopic resection with a positive lateral margin

Background and study aims: After noncurative endoscopic submucosal dissection (ESD) for differentiated-type early gastric cancer (EGC), close observation is often preferred when a cancer-positive lateral margin is the only noncurative factor. However, sometimes recurrence is found during the observation period. This study aimed to examine risk factors for recurrent cancer based on the long-term clinical outcomes after noncurative ESD in which the only noncurative factor was a cancer-positive lateral margin. Patients and methods: Among 3784 EGCs (3316 patients) treated by ESD between 1997 and 2010, 77 noncurative differentiated-type EGCs (75 patients) were retrospectively analyzed after meeting the following inclusion criteria: 1) the only noncurative factor was a cancer-positive lateral margin; 2) close observation was selected after the ESD; and 3) > 1 year follow-up after ESD. Results: Locally recurrent cancer was found in 10 lesions within a median follow-up period of 59.8 months; no metastasis or gastric cancer-related death occurred. The cumulative incidence of local recurrence 5 years after ESD was 11.9 %. All locally recurrent cancers were mucosal differentiated-type adenocarcinomas. Multivariate analysis indicated that a cancer-positive lateral margin length of >= 6mm was significantly associated with local recurrence (hazard ratio 20.8; 95% confidence interval 5.2%-82.9 %; P<0.001). The cut-off value of 6mm was determined by the receiver operating characteristic curve; the sensitivity and specificity for 5-year risk of developing local recurrence were 66.7% and 95.6 %, respectively. Conclusions: A cancer-positive lateral margin length of >= 6mm was an independent risk factor for local recurrence, and this may be a useful criterion for selecting high-risk cases for stricter management.