Identification of extracapsular invasion of the metastatic lymph nodes as a useful prognostic sign in patients with resectable colorectal cancer.

Abstract

The present study was undertaken to evaluate whether the microscopic patterns of distribution and extracapsular invasion of cancer cells in the regional lymph nodes were linked to the survival rates for patients with advanced colorectal cancer who undergo a curative surgical resection. Two hundred ninety-six surgically resected metastatic lymph nodes from 84 patients with node-positive colorectal cancer were microscopically examined. The distribution of cancer cells in the lymph nodes were grouped into two types: type A (> or =50 percent cancer) and type B (<50 percent cancer). The extracapsular invasion of cancer cells in the nodes were divided into three subgroups: pattern X (no evidence of cancer cell invasion into the adjacent tissue); pattern Y (less than five cancer cells were seen in the adjacent tissue); and pattern Z (more than five cancer cells invaded the adjacent tissue). The patients, based on these microscopic manifestations of metastatic patterns in the nodes, were divided into three groups: Group 1, patients with pattern X nodal metastases only; Group 2, patients with pattern Y and pattern (X + Y) nodal metastases; and Group 3, patients with pattern Z, pattern (X + Z), pattern (Y + Z), and pattern (X + Y + Z) nodal metastases. The survival rates and disease-free survival rates for patients with metastatic lymph nodes showing an extracapsular invasion pattern (Groups 2 and 3) were significantly worse than those for patients with metastatic nodes showing no extracapsular invasion pattern only (Group 1; P < 0.01). There was no significant difference for the above-cited survival rates among the groups classified according to the Dukes and TNM systems. It is the thesis of this article that the identification of extracapsular invasion of the metastatic lymph nodes can be taken as a useful prognostic sign in patients with resectable colorectal cancer.