Purpose
Vitamin D has been implicated in lowering lung cancer risk, but serological data on the association among never-smoking women are limited. We report results examining the association of serum 25-hydroxyvitamin D [25(OH)D] concentrations with lung cancer risk among female never smokers. We also examined whether the association was modified by vitamin D supplementation and serum vitamin A concentrations.
Methods
In the Women’s Health Initiative, including the Calcium/Vitamin D (CaD) Trial, we selected 298 incident cases (191 non-small-cell lung cancer [NSCLC] including 170 adenocarcinoma) and 298 matched controls of never smokers. Baseline serum 25(OH)D was assayed by a chemiluminescent method. Logistic regression was used to estimate odds ratios (ORs) for quartiles and pre-defined clinical cutoffs of serum 25(OH)D concentrations.
Results
Comparing quartiles 4 versus 1 of serum 25(OH)D concentrations, ORs were 1.06 (95% confidence interval [CI]=0.61-1.84) for all lung cancer, 0.94 (95% CI=0.52-1.69) for NSCLC, and 0.91 (95% CI=0.49-1.68) for adenocarcinoma. Comparing serum 25(OH)D ≥75 (high) versus <30 nmol/L (deficient), ORs were 0.76 (95% CI=0.31-1.84) for all lung cancer, 0.71 (95% CI=0.27-1.86) for NSCLC, and 0.81 (95% CI=0.31-2.14) for adenocarcinoma. There is suggestive evidence that CaD supplementation (1g calcium+400 IU D3/day) and a high level of circulating vitamin A may modify associations of 25(OH)D with lung cancer overall and subtypes (P-interaction <0.10).
Conclusions
In this group of never-smoking postmenopausal women, the results did not support the hypothesis of an association between serum 25(OH)D and lung cancer risk.