Number versus distribution in classifying regional lymph node metastases from colon cancer

Metastasis to regional lymph nodes from colon cancer is an important prognostic factor. In the TNM classification, node metastases are classified into three grades based on the number of metastatic nodes. In the Japanese General Rules for Clinical and Pathologic Studies on Cancer of the Colon, Rectum, and Anus (JGR), node metastases are classified into four grades based on the distribution of metastatic nodes.

Based on the findings of node metastases in 164 patients with colon cancer obtained by the clearing method, node classifications by the JGR and TNM classifications were compared.

The case distribution by the JGR grading was 41.5% in n (-), 29.3% in n1 (+), 18.3% in n2 (+), and 11.0% in n3 (+) disease. In the TNM classification, the distribution was 23.8% in pN1 and 34.8% in pN2 disease. The 5-year survival rate by the JGR was 98.4% in n (-), 74.3% in n1 (+), 51.2% in n2 (+), and 30.0% in n3 (+) disease; in TNM classification, this rate was 76.0% in pN1 and 45.0% in pN2 disease.

In the classification of regional node metastases from colon cancer, the JGR classification showed a wider range in distribution and 5-year survival rate compared with the TNM system.