Vitamin D levels differ by cancer diagnosis and decline over time in survivors of childhood cancer

Background: The aim of this study was to evaluate serum 25-hydroxyvitamin D (25OHD) concentrations in survivors of childhood cancer and compare levels by underlying diagnosis and as a function of time. Procedure: A retrospective review of 201 pediatric cancer survivors enrolled in a hospital-based cancer survivor registry. Demographic characteristics and 25OHD levels were extracted from the registry. Vitamin D status was determined during routine clinical care and was categorized as normal, insufficient, or deficient. Results: 25OHD levels differed significantly across diagnoses (P=0.017), with the lowest levels found in patients treated for osteosarcoma, retinoblastoma, hepatoblastoma, and myeloid leukemias. Age was inversely correlated with 25OHD levels (P=0.03). Average 25OHD level at study entry was 29.8ng/ml (range: 5-79.7), with 14.4% vitamin D deficient, 39.3% insufficient, and 46.3% normal. 25OHD concentrations decreased 11.4% over time (P<0.00001). Conclusion: Fewer than half of childhood cancer survivors have normal 25OHD concentrations, which further declined over time. Patients with solid tumors were the most affected, despite their lack of routine exposure to glucocorticoids. Future investigations should focus on why vitamin D level varies by diagnosis and how best to replete in this population.