Prevalence of occult peribronchial N1 nodal metastasis in peripheral clinical N0 <2 cm NSCLC

Abstract

There has been growing interest in limited resection and nonsurgical treatment for small lung cancers. Our objective was to examine the pattern and rate of occult N1 nodal metastasis in patients with peripheral, small (≤2 cm), clinically node-negative non-small cell lung cancer (NSCLC). Patients with peripheral <2 cm NSCLC with no evidence of locally advanced or metastatic disease (clinical T1a-bN0M0, 8 th edition) who were deemed eligible for either lobectomy or sublobar resection were identified from preregistration eligibility screening logs for the Alliance/CALGB 140503 trial at our institution. All patients undergoing anatomic resection with mediastinal and hilar lymphadenectomy were examined for pathologic outcomes. In total, 58 patients treated between November 2014 and January 2017 who met the inclusion criteria were included: 51 underwent lobectomy; 7 underwent segmentectomy. Mean tumor diameter on computed tomography was 1.5 cm, and mean positron emission tomography maximal standardized uptake value was 3.9; the mean consolidation-to-tumor ratio was 0.77. Eight of 58 patients (14%) had occult nodal metastases in N1 stations, and the majority of these nodes were found in interlobar or peribronchial stations (11 or 12). An additional 2 patients (3%) had occult positive N2 nodes. Overall, the false-negative rate for clinical staging was 16%. Occult nodal disease was frequently identified in peripheral N1 stations (11–13) in patients with small (≤2 cm) clinical N0 NSCLC. Hilar lymphadenectomy is essential for accurate staging in the management of patients with small clinical N0 NSCLC.