The prognostic impact of lymph-node dissection on lobectomy for pulmonary metastasis

OBJECTIVES: The prevalence and characteristics of lymph-node metastasis have not been thoroughly investigated in patients with pulmonary metastases from various primary neoplasms. The necessity of performing lymph-node dissection with pulmonary metastasectomy is unknown. METHODS: We retrospectively reviewed the database of the Metastatic Lung Tumor Study Group of Japan. Between November 1980 and June 2013, 4363 patients underwent resection of pulmonary metastases. After selecting for patients who underwent lobectomy, 683 patients (16%) were analysed. The presence of lymph-node metastasis, outcomes and prognoses were investigated. RESULTS: The primary tumour site was colorectal in 350 patients, head and neck in 73 patients, kidney in 41 patients, uterus in 41 patients and bone/soft tissue in 31 patients. The overall 5-year survival rate after pulmonary metastasectomy was 50.1%, and the 10-year survival rate was 36.4%. Lymph-node metastasis was more frequently found in uterine (27%) and head and neck cancers (29%). Five-year survival rates were 53.8% in patients without lymph-node metastasis, 39.4% in patients with hilar lymph-node metastasis and 30.8% in patients with mediastinal lymph-node metastasis. The extent of lymph-node dissection was not related to survival. Univariate analysis revealed that tumour size, the presence of lymph-node metastasis, the presence of multiple lesions, a disease-free interval of 24 months or less and incomplete resection were significant predictors of poor prognosis. Multivariate analysis confirmed these prognostic factors. CONCLUSIONS: Retrospective analysis of lobectomy for pulmonary metastasis demonstrated that lymph-node metastasis is a significant prognostic factor predicting poor outcome. Lymph-node sampling or dissection is therefore warranted to predict patient prognosis.