Objective: The aim of this study was to determine whether the risk of systemic disease after esophagectomy can be predicted by the number of involved lymph nodes. Summary Background Data: Primary esophagectomy is curative in some but not all patients with esophageal cancer. Identification of patients at high risk for systemic disease Would allow Selective use of additional systemic therapy. This study is a multinational, retrospective review of patients treated with resection alone to assess the impact of the number of involved lymph nodes on the probability of systemic disease. Methods: The study population included 1053 patients with esophageal cancer (700 adenocarcinoma, 353 squamous carcinoma) who underwent R-o esophagectomy with >= 15 lymph nodes resected at 9 international centers: Asia (1), Europe (5), and United States (3). To ensure a minimum potential follow-up of 5 years, only patients who had esophagectomy before October 2002 were included. Patients treated with neoadjuvant or adjuvant therapy were excluded. The impact of the number of involved lymph nodes on the risk of systemic disease recurrence was assessed using univariate and multivariate analyses. Results: Systemic disease Occurred in 40%. The number of involved lymph nodes ranged from 0 to 26 with 55% of patients having at least 1 involved lymph node. The frequency of systemic disease after esophagectomy was 16% for those without nodal involvement and progressively increased to 93% in patients with 8 or more involved lymph nodes. Conclusions: This study shows that the number of involved lymph nodes can be used to predict the likelihood of systemic disease in patients with esophageal cancer. The probability of systemic disease exceeds 50% when 3 or more nodes are involved and approaches 100% when the number of involved nodes is 8 or more. Additional therapy is warranted in these patients with a high probability of systemic disease.