Additive lymph node dissection may be necessary in minute submucosal cancer of the stomach after endoscopic resection

In early gastric cancer (EGC), minute submucosal (SM1) invasion of the stomach has been regarded as an expanded indication for endoscopic resection (ER). The exact prediction of SM1 invasion before ER may be difficult. Thus, SM1 invasion may be important to decide additive treatment after ER. This study was designed to investigate the incidence of lymph node metastasis (LNM) in SM1-EGC based on surgical specimens and to evaluate the factors that indicate additional treatment after ER.

From May 2005 to December 2008, 1,676 patients with EGC underwent surgery at Severance and Gangnam Severance Hospital, Seoul, Korea. Among them, 126 patients were diagnosed with differentiated SM1-EGC. The clinicopathologic characteristics were analyzed with respect to LNM and lymphovascular invasion (LVI), which is a known independent risk factor for LNM. Intratumoral marker immunohistochemistry was examined as a predictor of LVI.

The mean SM1 invasion depth was 621.3 ± 745.6 μm. The LNM rates did not differ significantly between differentiated SM1-EGC (6.3%) and SM1-EGC (4.1%) meeting the expanded indication for ER. Female gender, moderate differentiation, LVI, and LVI grade were positively correlated with LNM. Female gender and elevated lesion morphology were associated with LVI. The expression levels of VEGF-C and OPHN1 were higher in LVI-positive tissues.

The LNM rate in differentiated SM1-EGC meeting the expanded ER criteria was 4.1% in the present study, indicating that additional lymph node dissection may be necessary after ER in some cases of SM1-EGC.