RESUMEN
PURPOSE: Our previous analyses suggested that surgery in the summertime with higher vitamin D intake is associated with improved survival in patients with early-stage non-small-cell lung cancer (NSCLC). We further investigated the results of circulating 25-hydroxyvitamin D (25[OH]D) levels on overall survival (OS) and recurrence-free survival (RFS) in NSCLC patients. PATIENTS AND METHODS: Among 447 patients with early-stage NSCLC, data were analyzed using Cox proportional hazards models, adjusting for age, sex, stage, smoking, and treatment. RESULTS: The median follow-up time was 72 months (range, 0.2 to 141), with 161 recurrences and 234 deaths. For OS, the adjusted hazard ratio (AHR) was 0.74 (95% CI, 0.50 to 1.10; Ptrend = .07) for the highest versus lowest quartile of 25(OH)D levels. Stratified by stage, a strong association was observed among stage IB-IIB patients (AHR, 0.45; 95% CI, 0.24 to 0.82; Ptrend = .002), but not among stage IA patients (AHR, 1.10; 95% CI, 0.62 to 1.96; Ptrend = .53). Similar effects of 25(OH)D levels were observed among the 309 patients with dietary information (AHR, 0.74; 95% CI, 0.46 to 1.17; Ptrend = .19). For the joint effects of 25(OH)D level and vitamin D intake, the combined high 25(OH)D levels and high vitamin D intake (by median) were associated with better survival than the combined low 25(OH)D levels and low vitamin D intake (AHR, 0.64; 95% CI, 0.42 to 0.98; Ptrend = .06). Again, stronger associations were observed among stage IB-IIB than IA patients. Similar effects of 25(OH)D levels and vitamin D intake were observed for RFS. CONCLUSION: Vitamin D may be associated with improved survival of patients with early-stage NSCLC, particularly among stage IB-IIB patients.