OBJECTIVETo study the expression of gastric and intestinal phenotypic markers in gastric signet-ring cell (SRC) carcinoma and the relationship with the clinicopathologic parameters and prognosis.

METHODSImmunohistochemical study was carried out in 91 cases of early-stage SRC carcinoma using MUC1, MUC5AC and MUC6 antibodies as the gastric phenotypic markers and MUC2 and CDX2 antibodies as the intestinal phenotypic markers. According to the expression of phenotypic markers, the tumors were classified into three different subgroups: gastric, intestinal and mixed. The findings were analyzed together with various clinical parameters and follow-up data.

RESULTSAmongst the 91 cases studied, 53 cases (58.2%) belonged to gastric type, 22 cases (24.2%) mixed type and 16 cases (17.6%) intestinal type. The positive rates of MUC2 and CDX2 in early submucosal carcinoma were significantly higher than those in mucosal carcinoma (P < 0.01). On the other hand, the rates of MUC5AC and MUC6 expression in early submucosal carcinoma were significantly lower than those in mucosal carcinoma (P < 0.01 and P < 0.05). The rates of MUC2 and CDX2 expression in cases with lymph node metastasis and vascular invasion were significantly higher than those in cases without nodal or vascular involvement (P < 0.05). The expression of CDX2 was also significantly higher in cases with larger tumor size (P < 0.05). Cases with intestinal phenotype more likely had invasion deeper than mucosal layer and carried higher chance of lymph node metastasis (P = 0.000 and P = 0.003). Intestinal and mixed types correlated with shortened five-year survival.

CONCLUSIONSThe intestinal type of SRC carcinoma is associated with poorer biologic behavior and prognosis, as compared with that of the gastric type. Classification on the basis of immunophenotypic markers may be useful in predicting prognosis and guiding treatment for patients with gastric SRC carcinoma.