Background: The necessity of additional gastrectomy for patients not meeting the inclusion criteria after endoscopic submu cosal dissection (ESD) is controversial. The aim of this study was to elucidate the risk factors for lymph node metastasis (LNM) and residual cancer (RC) in patients not meeting the inclusion criteria after ESD and to determine additional treatment strategies.
Methods: Of 1443 gastric cancer patients who underwent ESD between 2004 and 2013, 167 patients diagnosed as having a lesion not meeting the inclusion criteria after ESD were retrospectively analyzed. Of the 167 cases, 100 cases underwent additional gastrectomy, and 67 cases were observed without surgery.
Results: Overall, 9.0 % (9/100) and 9.0 % (9/100) of patients not meeting the inclusion criteria after ESD presented with LNM and RC, respectively, but neither was observed in 83 patients (83.0 %). Multivariate analysis revealed that lymphovascular involvement (LVI) (OR 38.38; 95 % CI 1.94-761.43, p = 0.017) and undifferentiated type (OR 45.58; 95 % CI 2.88-720.94, p = 0.007) were independent risk factors for LNM, and positive horizontal margin was an independent risk factor for RC (OR 9.48; 95 % CI 1.72-52.13, p = 0.010). In differentiated types without LVI, no cases had LNM (0/38) in the additional gastrectomy group, and there was no lymph node or distant recurrence (0/39) in the observation group.
Conclusions: Additional treatment is necessary for patients with LVI, undifferentiated type, and positive horizontal margin. Careful follow-up may be acceptable for patients with the differentiated type without LVI, especially for the elderly or patients with severe comorbidities.
Keywords: Endoscopic submucosal dissection; Gastrectomy; Gastric cancer; Lymph node metastasis; Residual cancer; Risk factor.