Vitamin D deficiency and its relationship to cancer stage in patients who underwent thyroidectomy for papillary thyroid carcinoma.

Purpose: As imaging technology improves and more thyroid nodules and malignancies are identified, it is important to recognize factors associated with malignancy and poor prognosis. Vitamin D has proven useful as a prognostic tool for other cancers and may be similarly useful in thyroid cancer. This study explores the relationship of Vitamin D to papillary thyroid carcinoma stage while accounting for socioeconomic covariates. Materials and methods: The medical records of all patients who underwent thyroidectomy at one institution between 2000 and 2015 were reviewed. Subjects with non-papillary thyroid cancer pathology, prior malignancy, and without Vitamin D levels were excluded. The remaining 334 patient records were examined for cancer stage, Vitamin D levels, Vitamin D deficiency listed in history, and demographic and comorbid factors. Results: Vitamin D laboratory values showed no significant relationship to cancer stage (p = 0.871), but patients with Vitamin D deficiency documented in the medical record were more likely to have advanced disease (28.6% versus 14.7%; p = 0.028). The patients with documented Vitamin D deficiency also had lower 25-hydroxyvitamin D nadirs (21.5 ng/mL versus 26.5 ng/mL, p = 0.008) and were more likely to be on Vitamin D supplementation (92.6% versus 41.8%, p < 0.001). Conclusions: The results suggest that Vitamin D deficiency may have value as a negative prognostic indicator in papillary thyroid cancer and that pre-operative laboratory evaluation may be less useful. This is important because Vitamin D deficiency is modifiable. While different racial subgroups had different rates of Vitamin D deficiency, neither race nor socioeconomic status showed correlation with cancer stage.