Prognostic significance of the size of cancer nests in metastatic lymph nodes in human esophageal cancers

Background: Postoperative survival of patients with esophageal cancers after curative surgery is strongly affected by the presence of lymph node metastasis. The number and location of lymph node metastases have been evaluated and graded, but the clinical significance of their size has not been well investigated. Methods: Of 322 esophageal cancer patients who underwent curative operations with radical lymph node dissection, 170 (53%) had lymph node metastasis. A total of 784 metastatic lymph nodes were obtained, and the area of the cancer nests was measured microscopically in the cross section. The data from each patient included the area of the largest cancer nest in the positive nodes (N-max), classified as Na (<4 mm(2)), Nb (4-25 mm(2)), Nc (25-100 mm(2)), or Nd (> 100 mm(2)). Results: The 170 patients were classified according to the Nma, value: Na, 31 (18.2%); Nb, 35 (20.5%); Nc, 49 (28.8%); and Nd, 55 (32.4%). The 5-year survival rate was 77.7% in patients without lymph node metastasis and 35.4% in those with lymph node metastasis. When classified by Nmax, the 5-year survival rate was 77.8% for Na, 63.9% for Nb, 18.8% for Nc, and 12.8% for Nd. There was no significant difference in the survival rate between Na patients and those without lymph node metastasis. Nmax showed significant correlation with the primary tumor size, depth of tumor invasion, and number and location of metastatic lymph nodes, but not with histologic type or primary tumor location. In multivariate analysis, the Nmax value, the number of lymph node metastases and depth of tumor invasion were independent prognostic factors, while the location of the lymph node metastases was not statistically significant. Conclusions: The area of the largest cancer nest in the lymph nodes was one of the most significant prognostic factors for esophageal cancers. This estimation is objective and reproducible and may be of great importance when deciding the therapeutic modality for patients with esophageal cancers. J. Surg. Oncol. 2003;82:19-27. (C) 2002 Wiley-Liss, Inc.