Tumor growth patterns and biological characteristics of early gastric carcinoma

Gastric cancer is a major malignant disease. The development of new diagnostic techniques and mass screening have led to increased detection rates of patients with early-stage gastric cancer in Japan. However, after curative resection of early gastric cancer, there are various types of recurrences, and residual occult disease and distant micrometastasis precede death. The growth and metastatic potential of cancer cells are closely related to the postoperative outcome, and patients at risk for cancer-related death after surgery have to be closely monitored to prevent tumor recurrence. The biological behavior of cancer cells should be determined in patients with early gastric cancer and with a less favorable prognosis to detect potential early recurrences in the liver. Two types of growth patterns have been found in early gastric cancer: the superficially spreading (Super) type and the penetrating (Pen) type, and the clinicopathological and biological characteristics of each type have been extensively determined. A subtype of the Pen-type gastric cancer, which is progressing expansively with complete destruction of the muscularis mucosae (Pen A type) has a less favorable prognosis due to early recurrences in the liver. These clinical cancer types are closely related to chromosomal instability in DNA aneuploidy and p53 overexpression, and vascular endothelial growth factor activation induced tumor angiogenesis, vascular invasion and hematogenous metastasis. Thus, patients with Pen-A-type cancer showing expansive tumor growth had a poorer postoperative outcome and a hematogenous-related recurrence of the cancer. Antiangiogenic approaches in a postoperative setting may prove to be effective in preventing tumor recurrence and improving the prognosis for these patients.