Tumor infiltration pattern into the surrounding tissue has prognostic significance in advanced gastric cancer.

Gastric cancer can be classified into three subgroups according to pattern of tumor infiltration into the surrounding tissue: INFa (expanding growth and a distinct border with the surrounding tissue), INFc (infiltrating growth and an indistinct border with the surrounding tissue), and INFb (in-between a and c). How the tumor infiltration pattern (INF) relates to prognosis and type of recurrence in advanced gastric cancer has not been sufficiently explored. We examined 805 consecutive advanced gastric adenocarcinoma patients who underwent curative gastrectomy at our institution between 1980 and 2005. Poor differentiation, serosal invasion, and lymph node metastasis were significantly more frequent in patients with INFc tumors than in those with INFa/b tumors. For patients with a T2 or T3 tumor, there was no significant difference in prognosis between those with INFa/b and with INFc. However, for patients with a T4a or T4b tumor, the prognosis of those with INFc was significantly worse than that of those with INFa/b. In multivariate analysis, INF was an independent prognostic indicator in T4a but not T2, T3, and T4b. Furthermore, the prognosis of T4 patients with INFc tumors was significantly worse than that of those with INFa/b, especially in node-negative but not in node-positive cases. In patients with a T4a or T4b tumor, peritoneal recurrence was significantly more frequent for those with INFc than for those with INFa/b. Our data indicate that INF is useful to predict the prognosis and recurrence pattern in T4a node-negative gastric cancer.