Assessment of the Nodal Status in Ampullary Carcinoma: The Number of Positive Lymph Nodes Versus the Lymph Node Ratio

This study was intended to compare the prognostic power of the number of positive lymph nodes with that of the lymph node ratio in patients with ampullary carcinoma. A retrospective analysis was conducted of the medical records of 71 consecutive patients with ampullary carcinoma who underwent pancreaticoduodenectomy with regional lymph node dissection. A total of 2151 lymph nodes were dissected (median: 28 nodes per patient) and examined histologically. Cutoff points were determined for both the number of positive nodes and the lymph node ratio using chi(2) scores calculated with the Cox proportional hazards regression model. Lymph node metastasis was found in 34 patients. The best cutoff point for the number of positive nodes was identified as three nodes, and that for the lymph node ratio was identified as 10%. Univariate analysis revealed both the number of positive nodes (0, 1-3, or a parts per thousand yen4; P < 0.0001) and the lymph node ratio (0%, 0-10%, or > 10%; P < 0.0001) as significant prognostic factors. Multivariate analysis identified the number of positive nodes as an independent prognostic factor (P < 0.001), whereas the lymph node ratio failed to remain as an independent variable. The cumulative 5-year survival rates were 85% for patients with 0 positive nodes, 63% for patients with 1-3 positive nodes, and 0% for patients with a parts per thousand yen4 positive nodes (P < 0.0001). The number of positive lymph nodes better predicts the outcome after resection than the lymph node ratio in patients with ampullary carcinoma.