The impact of lymph node yield on Duke's B and C colorectal cancer survival

Aim The number of positive lymph nodes retrieved following colorectal cancer (CRC) resection impacts on the staging and further treatment of the disease. We compared 5-year survival by lymph node yield for Duke's B and C patients to assess the impact on prognosis. Method A retrospective methodology was employed to review patients who underwent operative resection for Duke's B or C CRC between 1999 and 2003. Results A total of 351 patients were included in our analyses. Lymph node yield, N-stage and extramural vascular invasion were independent predictors of overall 5-year survival. A significant difference in 5-year survival by lymph node yield was seen among Duke's B patients (< 9 nodes vs >= 9 nodes, 45.2%vs 68.4%; P = 0.0043) and Duke's C patients (< 10 nodes vs >= 10 nodes, 25.6%vs 48.8%; P = 0.0099). There was a significant reduction in the relative risk of 2.8% in mortality for each additional node sampled in Duke's B and C patients (RR 0.972, 95% confidence interval 0.949-0.994, P = 0.0102). Duke's B patients who had < 9 lymph node yield and no neoadjuvant/adjuvant treatment had a similar survival to all Duke's C patients (47.8%vs 41.7%, P = 0.5136). Conclusion Lymph node yield independently predicts for survival in patients with Duke's B and C CRC. Duke's B patients with < 9 lymph node yield have no better survival than patients with Duke's C disease. Therefore, prospective randomized studies are required to examine if inadequate lymph node yield could be one of the deciding factors in offering adjuvant therapy among Duke's B cancer patients.