Association of serum 25-hydroxyvitamin D levels with aggressiveness of papillary thyroid cancer

Objective Serum 25-hydroxyvitamin D (25(OH)D) deficiency has been known to be associated with the risk and mortality of several cancers. However, the role of 25(OH)D in papillary thyroid cancer (PTC) remains controversial. This study aimed to investigate the association between 25(OH)D and clinicopathologic features of PTC. Methods Patients who underwent thyroidectomy were retrospectively reviewed. Serum 25(OH)D levels were measured within a week prior to surgery. The patients were categorized into four quartiles according to season-specific 25(OH)D levels. The association between 25(OH)D levels and clinicopathologic features of PTC was analyzed. Results A total of 2932 patients were enrolled in the study. The 25(OH)D levels were significantly higher in patients with lymph node metastasis (LNM; P < 0.001), lateral LNM ( P < 0.001), and multifocal tumors ( P < 0.001). Compared to the first quartile (Q1) of 25(OH)D level, the third quartile (Q3) and the fourth quartile (Q4) showed an unadjusted OR of 1.36 (95% CI: 1.09–1.69; P = 0.006) and 1.76 (95% CI: 1.42–2.19; P < 0.001) for LNM ( P for trend < 0.001), respectively. An increased risk of multifocal tumors was strongly associated with high 25(OH)D concentration ( P for trend <0.001). Similar results were obtained after adjusting for confounding factors. Conclusion High 25(OH)D levels are associated with aggressive features of PTC, such as lymph node metastasis and multifocality.