Mandatory Nodal Evaluation During Resection of Clinical T1a Non-Small-Cell Lung Cancers

Abstract Background Recommendations for intraoperative lymph node evaluation are uniform regardless of whether a primary tumor is clinical T1a or T2a according to TNM 8th edition for Stage I Non-Small-Cell lung cancers (NSCLC). We quantified nodal disease risk in patients with T1a disease (≤1cm). Methods The National Cancer Database was queried for clinical T1aN0M0 primary NSCLCs ≤1cm undergoing lobectomy with mediastinal nodal evaluation from 2004-2014. Nodal disease risk was analyzed as a function of demographics and tumor characteristics. Results Among 2,157 cases, 6.7% had occult nodal disease: 5.1% occult N1 and 1.6% N2. Adenocarcinoma (7.5%), large cell carcinoma (25%), and poor differentiation (11.8%) or undifferentiated/anaplastic (25.0%) had high rates of combined pN1 and N2 disease (p Conclusions A significant rate (6.7%) of occult nodal disease is present in primary NSCLCs ≤1cm. Risk increases with certain histology and worsening grade. We recommend mandatory systematic hilar and mediastinal nodal evaluation for T1a NSCLC tumors for accurate staging and adjuvant therapy.