Number of lymph nodes harvested from a mediastinal lymphadenectomy: Results of the randomized, prospective American College of Surgeons Oncology Group Z0030 trial

Background: Lymph node status is a major determinant of stage and survival in patients with lung cancer; however, little information is available about the expected yield of a mediastinal lymphadenectomy. Methods: The American College of Surgeons Oncology Group Z0030 prospective, randomized trial of mediastinal lymph node sampling vs complete mediastinal lymphadenectomy during pulmonary resection enrolled 1,111 patients from July 1999 to February 2004. Data from 524 patients who underwent complete mediastinal lymph node dissection were analyzed to determine the number of lymph nodes obtained. Results: The median number of additional lymph nodes harvested from a mediastinal lymphadenectomy following systematic sampling was 18 with a range of one to 72 for right-sided tumors, and 18 with a range of four to 69 for left-sided tumors. The median number of N2 nodes harvested was 11 on the right and 12 on the left. A median of at least six nodes was harvested from at least three stations in 99% of patients, and 90% of patients had at least 10 nodes harvested from three stations. Overall, 21 patients (4%) were found to have occult N2 disease. Conclusions: Although high variability exists in the actual number of lymph nodes obtained from various nodal stations, complete mediastinal lymphadenectomy removes one or more lymph nodes from all mediastinal stations. Adequate mediastinal lymphadenectomy should include stations 2R, 4R, 7, 8, and 9 for right-sided cancers and stations 4L, 5, 6, 7, 8, and 9 for left-sided cancers. Six or more nodes were resected in 99% of patients in this study. Trial registry: ClinicalTrials.gov; No.: NCT00003831; URL: clinicaltrials.gov.