[Association of adenylate cyclase-associated protein 2 expression with histopathology and long-term prognosis of gastric cancer].

OBJECTIVE:To explore association of the expression levels of adenylate cyclase-associated protein 2 (CAP2) in gastric cancer tissues with the histopathology and long-term prognosis of the malignancy. METHODS:This study was conducted among a total of 105 patients with gastric cancer undergoing radical gastrectomy in our hospital between January, 2010 and October, 2013. Immunohistochemistry was used to quantitatively assess the expression of CAP2 in gastric cancer tissues and the adjacent tissues. Based on the median relative expression level of CAP2 of 3.5, the patients were divided into low CAP2 expression group (n=52) and high CAP2 expression group (n=53). The Cox regression model was used to analyze the effect of CAP2 expression on the 5-year survival rate of the patients, and ROC curve analysis was used to assess the predictive value of CAP2 expression for the patients' long-term survival. RESULTS:Immunohistochemical analysis showed that the expression levels of CAP2 (P < 0.01) and Ki67 (P < 0.01) were significantly higher in gastric cancer tissues than in the adjacent tissues, and the expression level of CAP2 was positively correlated with Ki67 (P < 0.01), peripheral blood CEA (P < 0.01) and CA19-9 (P < 0.01). The percentages of patients with CEA≥5 μg/L, CA19-9≥37 kU/L, pathological grade of G3-G4, T stage of 3-4, and N stage of 2-3 were significantly higher in patients with high CAP2 expression than in those with low CAP2 expression (P < 0.05). Kaplan- Meier survival analysis showed that the 5-year survival rate was significantly lower in patients with a high CAP2 expression (P < 0.01). A high expression level of CAP2, CEA≥5μg/L, CA19-9≥37 and pathological grades G3-G4 were all independent risk factors for shortened 5-year survival after radical gastrectomy (P < 0.01). With the relative expression level of 3.45 as the cut-off value, the sensitivity of CAP2 was 70.15% for predicting death 5 years after the surgery, with a specificity of 71.05% and an area under the curve of 0.779 (P < 0.01). CONCLUSIONS:CAP2 is highly expressed in gastric cancer tissues in close relation with the tumor progression. CAP2 is an independent risk factor for 5-year survival rate after radical gastrectomy for gastric cancer and can be of clinical value in prognostic evaluation of the patients.

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