Total, bioavailable and free 25-hydroxyvitamin D are associated with the prognosis of patients with non-small cell lung cancer

Abstract

Purpose: To analyze the prognostic value of total, bioavailable and free 25-hydroxyvitamin D [25(OH)D] as well as vitamin D-binding protein (VDBP) in patients with non-small cell lung cancer (NSCLC).

Methods: We prospectively collected and analyzed data for 395 patients diagnosed with NSCLC between January 2016 and December 2018 in two university-affiliated hospitals. Total and free 25(OH)D and VDBP were measured directly, and bioavailable 25(OH)D was calculated using a validated formula. Their prognostic values were evaluated by Cox proportional hazards model, and hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated.

Results: Patients with NSCLC had significantly lower levels of total, bioavailable, and free 25(OH)D and higher VDBP levels in comparison to healthy controls (all p < 0.001). In multivariate analyses, higher levels of total, bioavailable, and free 25(OH)D were independently associated better overall survival (OS) and progression-free survival (PFS). For OS, the adjusted HRs were 0.58 (95% CI, 0.40-0.87; p for trend = 0.008), 0.45 (95% CI, 0.30-0.67; p for trend < 0.001) and 0.49 (95% CI, 0.33-0.73; p for trend < 0.001) for the highest versus the lowest tertile of total, bioavailable and free 25(OH)D, respectively. The corresponding adjusted HRs for PFS were 0.61 (95% CI, 0.43-0.86; p for trend = 0.006), 0.56 (95% CI, 0.40-0.80; p for trend = 0.001) and 0.60 (95% CI, 0.42-0.85; p for trend = 0.004), respectively. However, VDBP was not associated with either OS or PFS.

Conclusion: The current study suggested that total, bioavailable and free 25(OH)D may be reliable prognosis indicators in NSCLC patients, though the optimal 25(OH)D form for NSCLC prognosis remains to be assessed in future studies.

Keywords: Bioavailability; NSCLC; Survival; Vitamin D; Vitamin D-binding protein.