Low Serum 25 Hydroxyvitamin D Is Associated with Poor Clinicopathologic Characteristics in Female Patients with Papillary Thyroid Cancer

Background: Vitamin D has recently attracted attention because reduced levels are associated with the prevalence and aggressiveness of several cancers. This study aimed to evaluate the relationship between preoperative serum 25 hydroxyvitamin D (25(OH) vitamin D) levels and clinicopathologic characteristics in female patients with papillary thyroid cancer (PTC). Methods: A total of 548 female patients who underwent total thyroidectomy for PTC between June 2012 and May 2013 were included. Blood samples were obtained within two weeks prior to surgery. Patients were categorized into four quartiles by preoperative serum 25(OH) vitamin D levels. The clinicopathologic features of PTC were analyzed retrospectively. Results: Preoperative 25(OH) vitamin D was significantly lower in patients with a tumor size of >1 cm (p=0.041) or lymph node metastasis (LNM; p=0.043). No significant trends in several clinicopathologic features were observed in relation to increasing serum vitamin D concentrations except decreasing tumor size (p=0.010). Patients in the second quartile had a greater occurrence of T stage 3/4 (odds ratio (OR) 2.03 [confidence interval (CI) 1.19–3.44]; p=0.009), LNM (OR 2.03 [CI 1.19–3.44]; p=0.009), lateral LNM (OR 5.03 [CI 1.66–15.28]; p=0.004), and extrathyroidal extension (ETE; OR 1.95 [CI 1.15–3.29]; p=0.013) than those in the fourth quartile. Multivariate analysis showed that patients in the second quartile had a greater occurrence of T stage 3/4 (OR 1.89 [CI 1.08–3.30]; p=0.026), LNM (OR 2.04 [CI 1.20–3.47]; p=0.009), lateral LNM (OR 5.12 [CI 1.68–15.59]; p=0.004), and ETE (OR 1.81 [CI 1.04–3.15]; p=0.036) than those in the fourth quartile. When the subjects were recategorized into two groups by median 25(OH) vitamin D levels, those with values below the median had a significantly higher risk of T stage 3/4, LNM, lateral LNM, stage III/IV, and ETE. All values except ETE sustained significance after adjustment. Conclusion: Lower preoperative serum 25(OH) vitamin D levels appear to be associated with poor clinicopathologic features in female patients with PTC.