Prognostic significance of functional capacity and exercise behavior in patients with metastatic non-small cell lung cancer

Background: To investigate the prognostic importance of functional capacity and exercise behavior in patients with metastatic non-small cell lung cancer (NSCLC). Patients and methods: Using a prospective design, 118 consecutive participants with histologically confirmed metastatic (inoperable) NSCLC and Eastern Cooperative Oncology group (ECOG) 0-3 completed a six-minute walk test to assess functional capacity and questionnaire that assessed self-reported exercise behavior. Cox proportional models were used to estimate the risk of all-cause mortality according to six-minute walk distance (6MWD) (<358.5m, 358.5-450m, ≥450m) and exercise behavior (MET-hrswk^-1) categories with adjustment for important covariates. Results: Median follow-up was 26.6 months; 77 deaths were reported during this period. Functional capacity was an independent predictor of survival (P_trend=0.003) and added incremental prognostic value beyond that provided by PS plus other traditional markers of prognosis (P_trend=0.025). Compared with patients achieving a 6MWD <358.5m, the adjusted hazard ratio (HR) for all-cause mortality was 0.61 (95% CI, 0.34-1.07) for a 6MWD of 358.5-450m, and 0.48 (95% CI, 0.24-0.93) for a 6MWD >450m. In unadjusted analysis, there was a borderline significant effect of exercise behavior on survival (p=0.052). Median survival was 12.89 months (95% CI, 9.11-21.05 months) for those reporting <9MET-hrswk^-1 compared with 25.63 months (95% CI, 11.28 to ∞ months) for those reporting ≥9MET-hrswk^-1. Conclusions: Functional capacity is a strong independent predictor of survival in advanced NSCLC that adds to the prediction of survival beyond traditional risk factors. This parameter may improve risk stratification and prognostication in NSCLC.