Histologic grade of metastatic lymph node and prognosis of rectal cancer

PURPOSE: It is important to identify cases with a high risk of recurrence t o improve the prognosis of colorectal cancer. In this study the difference between the histology of the primary lesion and that of the metastatic lymp h node was investigated in an attempt to identify the cases with a high ris k of recurrence. METHODS: One-hundred eighty-five patients with Dukes C rec tal cancer who had undergone curative resection were investigated. The hist ologic grade of the metastatic lymph node was determined and compared with other clinicopathologic factors to determine its significance as a prognost ic factor. RESULTS: The histologic grade was the same between the primary l esion and the metastatic lymph node in 46.2 percent of all cases, although in the group with well-differentiated adenocarcinoma at the primary lesion the concordance was only 29.5 percent. In the group with well-differentiate d adenocarcinoma at the primary lesion, the five-year survival rate was 75. 3, 64, and 25 percent in the groups with well-differentiated, moderately di fferentiated, and poorly differentiated adenocarcinoma at the metastatic ly mph node, respectively. The differences between the survival rates of well- differentiated and poorly differentiated adenocarcinoma at the metastatic l ymph node were statistically significant (P < 0.05). According to multivari ate analysis the histologic grade of primary lesion was the most significan t prognostic factor (hazard ratio: 2.2801, P = 0.0008). However, in well-di fferentiated adenocarcinoma of patients with Dukes C rectal cancer at the p rimary lesion, the histology of metastatic lymph node was also an important prognostic factor. CONCLUSIONS: It is clear that the histologic grade betw een the primary lesion and metastatic lymph node was frequently different, especially in the group with well-differentiated adenocarcinoma at the prim ary lesion. The analysis of the metastatic lymph node was considered to hav e additional importance for the prediction of prognosis.