T4 extension alone is more predictive of better survival than a tumour size >7 cm for resected T4N0-1M0 non-small-cell lung cancer

OBJECTIVES T4N0-1 non-small-cell lung cancer (NSCLC) was historically considered curable but now includes tumours of size >7 cm according to the 8th edition tumour, node and metastasis (TNM) staging. This study was set out to evaluate the role of surgery and predictors of long-term survival after surgery in this renewed group of patients. METHODS Patients, with clinical T4N0-2M0 NSCLC diagnosed in 2010-2013, in the National Cancer Database were queried. A Cox regression analysis was applied to investigate independent predictors of survival in 1588 N0-1 surgical cases. For previous T3 cases, the efficacy of treatment including and not including surgery was compared after propensity score matching by age, gender, race, facility type, comorbidity, laterality, clinical N stage, histology and tumour grade. RESULTS In newly defined T4N0-1 NSCLC patients undergoing surgery, age, gender, comorbidity, nodal status, resection margin, tumour grade, chemotherapy and extension-size group were shown to be independent predictors of survival. In particular, patients with only T4 extension showed better survival than patients with tumour size >7 cm only [hazard ratio (HR) 0.75, 95% confidence interval (CI) 0.62-0.92, P = 0.016]. In the latter group, surgical treatment was associated with better survival than non-surgical treatment after matching (HR 0.45, 95% CI 0.42-0.48, P < 0.001). CONCLUSIONS In the newly defined T4 NSCLC, tumour size >7 cm is a descriptor that is more predictive of worse survival than local extension alone for patients whose treatment included surgery. For T4-extended, N0-1 NSCLC with a tumour size ≤7 cm, surgery might be associated with favourable long-term outcomes and should be further encouraged as a treatment option.