Risk Factors for Lymph Node Metastasis from Gastric Cancers with Submucosal Invasion

Accurate prediction of the metastatic status of lymph nodes (LNs) is clinically important for selecting treatment strategies in patients with gastric cancer with submucosal invasion (GCSM). In this study, we determined the risk factors for lymph node metastasis (LNM), including micrometastasis, in patients with GCSM. A total of 5610 LNs dissected from 189 patients with GCSM who had undergone a standard gastrectomy were immunostained with CAM 5.2 monoclonal antibody to detect LN micrometastasis. Clinicopathological risk factors for lymph node metastasis (LNM), including micrometastasis, were determined. LNM was detected in 216 LNs (107 macroscopic metastases, 72 micrometastases, and 37 isolated tumor cells) in 55 (29.1%) of the 189 patients with GCSM. A multivariate analysis revealed that a tumor size of more than 20 mm, a mixed- or undifferentiated-type histology, a vertical tumor invasion depth in the submucosal layer (VTIDSM) of more than 0.5 mm, and the presence of lymphatic vessel invasion (LVI) were independent risk factors for LNM. The incidences of LNM in patients with 0, 1, 2, 3, and 4 risk factors were 0, 4.5, 11.4, 36.1, and 52.9%, respectively. Among the patients with only 1 or 2 risk factors, all the metastatic lesions were located only in the first tier. On the other hand, LNM in the second tier was also detected in 24.5% of the patients with more than 3 risk factors. Tumor size, histologic type, VTIDSM, and LVI are important risk factors for predicting the presence and extent of LNM in patients with GCSM.