Effect of double-layer structure in intramucosal gastric signet-ring cell carcinoma on lymph node metastasis: a retrospective, single-center study.

Background: Among all types of gastric cancer (GC), signet-ring cell carcinoma (sig-GC) accounts for 4-17% of cases. The prognosis of early sig-GC is relatively good, with the 5-year survival rate at 99.7%. However, the correlation between histological features and lymph node metastasis (LNM) among pT1a (M) sig-GC remains unclear. Sig-GC often exhibits a double-layer structure (DLS) in the intramucosal layer, demonstrating functional differentiation into the normal gastric gland. Assumedly, the loss of the differentiation makes the DLS deranged, accounting for the occurrence of submucosal invasion and LNM. This study aimed to assess the proportion of DLS, to elucidate the correlation between histological features (including DLS) and LNM status, and to determine the LNM-negative condition in pT1a (M) sig-GC.

Methods: We reviewed the pathological data of 310 patients with 310 intramucosal sig-GCs who received gastrectomy with lymph node dissection. Immunohistochemistry was performed on all specimens to evaluate the presence of DLS. Furthermore, we review the clinicopathological features, including tumor size, lymphovascular invasion (LVI), ulceration (UL), and DLS results, and then statistically analyze the correlation between these features and LNM status.

Results: Overall, 129 pT1a (M) sig-GCs (42%) were DLS present. The univariate analysis revealed that "Tumor size > 20 mm", "UL present", and "DLS absent" were significant risk factors of LNM. The multivariate logistic regression analysis revealed only "DLS absent" as statistically significant.

Conclusions: "DLS absent" is a risk factor of LNM detected by the multivariate analysis. In pT1a (M), LVI absent, UL absent, tumor size > 20 mm, sig-GC, no LNM occurred in "DLS present" cases.