Invasive Staging Procedures Do Not Prevent Nodal Metastases From Being Missed in Stage I Lung Cancer

Abstract

Up to 20% of clinical stage I lung cancer patients harbor lymph node metastases that go undetected (missed) during the clinical staging evaluation. We investigated to what degree the addition of invasive nodal staging procedures to imaging, as currently practiced, prevents radiographically occult nodal metastases from being missed during the clinical staging evaluation. Treatment-naive patients, imaged by positron emission tomography and computed tomography, who underwent lobectomy for clinical stage I lung cancer from 2012 to 2017 in The Society of Thoracic Surgeons General Thoracic Surgery Database were studied. Rates of missed nodal metastases (MNM) (ie, nodal metastases in lobectomy specimens undetected during clinical staging evaluation) were determined. Risk factors were assessed with multivariable modeling. Of the 30,685 clinical stage I patients identified, 3895 (12.7%) underwent preoperative endobronchial ultrasound and 3341 (10.9%) underwent mediastinoscopy. Invasive staging was more common with tumors > 2 cm (66.4% vs 50.2%, P < .001) and squamous histology (26.9% vs 16.9%, P < .001). MNM were discovered in 14.7% of patients, including 20.1% of patients (95% confidence interval, 18.8%-21.5%) who had undergone endobronchial ultrasound and 18.2% (95% confidence interval, 16.7%-19.6%) who had undergone mediastinoscopy. Hilar nodes were most often "missed" (9.5%). Using cut-points in tumor size, histology, laterality, and age, patients could be stratified into particularly high-risk (25% MNM) and low-risk (6% MNM) cohorts. Substantial risk of occult lymph node metastases persists in patients with clinical stage I lung cancer despite negative invasive nodal staging, positron emission tomography, and computed tomography. In the absence of a thorough surgical nodal evaluation, early-stage lung cancer patients are at risk of under-treatment.