BACKGROUND AND AIM Although more than 80% of undifferentiated early gastric cancers (EGC) are not associated with lymph node metastasis, endoscopic mucosal resection is not generally accepted as a means of curative treatment because of an abundance of conflicting data concerning clinicopathological characteristics and prognoses. The aim of this study was to define a subgroup of undifferentiated EGC that could be cured by endoscopic treatment without the risk of lymph node metastasis.

METHOD A total of 591 patients surgically resected for undifferentiated EGC between January 1999 and March 2005 were reviewed. Associations between various clinicopathological factors and the presence of lymph node metastasis were analyzed to identify the risk factors of lymph node metastasis.

RESULTS Lymph node metastasis was found in 79 patients (13.4%). By multivariate logistic regression analysis, a tumor diameter 2.5 cm or larger, invasion into the middle third of the submucosal layer or deeper, and lymphatic involvement were identified as independent risk factors of lymph node metastasis (P < 0.001, respectively). Lymph node metastasis was not found in any patient with undifferentiated EGC smaller than 2.5 cm confined to the mucosa or upper third of the submucosal layer without lymphatic involvement.

CONCLUSIONS Undifferentiated intramucosal EGC smaller than 2.5 cm without lymphatic involvement was not associated with lymph node metastasis. Thus, we propose in this circumstance that endoscopic mucosal resection could be considered a definitive treatment without compromising the possibility of cure.