Missed Intrapulmonary Lymph Node Metastasis and Survival After Resection of Non-Small Cell Lung Cancer

Background. Pathologic nodal stage is a key prognostic factor for patients with surgically resected lung cancer. We previously described the extent of missed intrapulmonary nodal metastasis in a cohort of patients treated at institutions in metropolitan Memphis, TN. With long-term follow-up, we now quantify the survival impact of missed nodal metastasis. Methods. We conducted a prospective cohort study to evaluate inadvertently discarded lymph nodes in re-dissected remnant lung resection specimens from lung cancer patients. Retrieved material was histologically examined and classified as lymph nodes with and without metastasis. Survival information was obtained from hospital cancer registries. We plotted survival distributions with the use of the Kaplan-Meier method and evaluated them with proportional hazards models that controlled for important demographic and clinical factors. Results. The study included 110 patients who were 54% women and 69% white. Discarded lymph nodes with metastasis were found in 25 patients (23%). Patients with missed lymph node metastasis had an increased risk of death with an unadjusted hazard ratio of 2.0 (p = 0.06) and an adjusted hazard ratio of 1.4 (p = 0.45) compared with patients without missed lymph node metastasis. Patients with more than 2 missed lymph nodes with metastasis had 4.8 times the hazard of death (p = 0.0005) compared with patients without missed lymph node metastasis (adjusted hazard ratio 6.5, p = 0.0001). Conclusions. Metastasis to inadvertently discarded intrapulmonary lymph nodes from lung cancer resection specimens was associated with reduced survival. A more rigorous gross dissection protocol for lung cancer resection specimens may provide prognostically useful information. (C) 2016 by The Society of Thoracic Surgeons