Should we operate on microscopic N2 non-small cell lung cancer?

Traditionally non-small cell lung cancer (NSCLC) stage N2 is considered as a contraindication for curative resection. We investigated the outcome of patients with microscopic N2 disease, who underwent potentially curative resections. The independent effects of lobectomy vs. pneumonectomy, histology subtype, body mass index (BMI), sex, and PET-scanning were investigated. An N2 survival risk score was calculated and correlated with survival. Benchmarking revealed no discrepancies in our stage-specific survival data against the seventh edition of the International Association for the Study of Lung Cancer (IASLC) results. Of 1999 lung resections for primary lung cancer, 146 were pathologically staged as N2. Patients with resected microscopic N2 disease had a five-year survival equivalent to stage T3N1, P=0.39. Univariate analysis suggested pneumonectomy and T stage 3 as significant predictors of poor survival. Cox multivariate regression analysis revealed that age, BMI>30 kg/m(2), pneumonectomy, squamous type and positron emission tomography (PET)-scan all had a significant effect on survival, P<0.05. A low N2 survival risk score was associated with increased survival, P=0.001. Resecting microscopic N2 disease in NSCLC may be appropriate in some patients. An N2 survival scoring system may help select patients for surgery, and help evaluate adjuvant and neoadjuvant publications with regard to microscopic N2 disease.