Purpose: The objective of this study was to determine the number of nodes that need to be examined to accurately reflect the histology of the regional lymphatics in colorectal carcinoma.
Patients and methods: Patients undergoing curative resection for T2 and T3 colorectal cancer between 1992 and 1996 were reviewed. Pathologic data from these patients were entered into a computerized database for storage, retrieval, and analysis. The major outcome measured was the number of nodes that need to be examined to achieve a node-positive rate consistent with that reported in the National Cancer Data Base (NCDB) report.
Results: The number of nodes examined ranged from 0 to 78 (mean, 17 nodes). Node-negative patients had fewer nodes examined (mean, 14 nodes) than node-positive patients (mean, 20 nodes; P =.003). The entire sample had a node-positive rate of 38.8% (95% confidence interval [CI], 32% to 45.5%), not statistically different from that in the NCDB report. When at least 14 nodes were examined, the percent of patients with at least one positive node was 33.3% (95% CI, 24.6% to 42.3%), not statistically different from the NCDB report.
Conclusion: In a sample of patients statistically similar to the sample in the NCDB report, the examination of at least 14 nodes after resection of T2 or T3 carcinoma of the colon and rectum will accurately stage the lymphatic basin.