Prognostic role of lymph node involvement in lung metastasectomy

Objective: The impact of lymph node involvement in lung metastasectomy from extrapulmonary malignancies is uncertain. We assessed the prognostic value of lymph node status in lung metastasectomy and the prevalence of unexpected mediastinal lymph node involvement after lymph node sampling or dissection. Methods: From May 1998 to October 2005, 388 patients underwent 430 pulmonary metastasectomies with curative intent. The clinical records of all patients who underwent radical lymph node dissection or sampling were reviewed retrospectively. Survival was evaluated using the Kaplan-Meier method and comparison of survival curves by log-rank test. Results: A total of 124 patients ( 61 men, mean age 59 years) underwent 139 pulmonary metastasectomies ( 56 wedge resections, 30 segmentectomies, 49 lobectomies, and 4 pneumonectomies with radical lymph node dissection [ 88] or sampling [ 51]). Means of 9.4 lymph nodes and 2 lung metastases per intervention were removed. The median disease-free interval from primary treatment to lung metastasectomy was 49 months. Lymph node involvement was present in 25 patients (20%), in 10 ( 8%) at N1 stations (hilar or peribronchial) and in 15 (12%) at N2 stations ( mediastinal), and in 7 (12.5%) after atypical resection and in 19 (23%) after typical resection. In 15 patients ( 12%) (60% of N+ patients), lymph node involvement was unexpected. Estimated overall 5-year survival was 46%: It was 60% for subjects with no lymph node metastasis and 17% and 0% for those with N1 and N2 disease, respectively (P=.01). Conclusions: Lymph node involvement heavily affects prognosis after pulmonary metastasectomies. In most patients, lymph node involvement was not revealed by preoperative workup.