The Role of an Undifferentiated Component in Submucosal Invasion and Submucosal Invasion Depth After Endoscopic Submucosal Dissection for Early Gastric Cancer.

Background/aims: The role of an undifferentiated component in submucosal invasion and submucosal invasion depth (SID) for lymph node metastasis (LNM) of early gastric cancer (EGC) with deep submucosal invasion (SID ≥500 μm from the muscularis mucosa) after endoscopic submucosal dissection (ESD) has not been fully understood. This study aimed to clarify the risk factors (RFs), including these factors, for LNM in such patients.

Methods: We enrolled 513 patients who underwent radical surgery after ESD for EGC with deep submucosal invasion. We evaluated RFs for LNM, including an undifferentiated component in submucosal invasion and the SID, which was subdivided into 500-999, 1,000-1,499, 1,500-1,999, and ≥2,000 µm.

Results: LNM was detected in 7.6% of patients. Multivariate analysis revealed that an undifferentiated component in submucosal invasion (OR 2.22), in addition to tumor size >30 mm (OR 2.51) and lymphatic invasion (OR 3.07), were the independent RFs for LNM. However, the SID was not significantly associated with LNM.

Conclusion: An undifferentiated component in submucosal invasion was one of the RFs for LNM, in contrast to SID, in patients who underwent ESD for EGC with deep submucosal invasion. This insight would be helpful in managing such patients.