Vitamin D Levels in Pediatric Patients Undergoing Chemotherapy

Abstract

Background: Vitamin D has important roles in bone health, immune function, metabolic regulation, and cancer. Children with cancer may be especially vulnerable to fluctuating Vitamin D levels due to their disease itself, chemotherapy, and limited nutrition and sun exposure. However, most US-based literature addresses only childhood cancer survivors after therapy concluded, so it remains unclear if children with cancer are at risk of vitamin D deficiency during treatment. Methods: This study investigated (i) if children with cancer are vitamin D deficient compared to matched controls, (ii) if their vitamin D levels worsen throughout the course of their cancer treatment, and (iii) if vitamin D levels correlate with the number of fever episodes or fever severity score, as surrogate for infectious disease, in cancer patients. The serum levels of 25-hydroxycholecalciferol vitamin D (25OHD) were assessed at baseline (T1, both cancer and control groups) and 3-4 months and 6-8 months later (T2 and T3, cancer group only). Any incidence of fever experienced in patients with cancer during the study period was recorded and a previously-validated fever severity score was calculated for each episode. Results: This prospective cohort study enrolled 47 cancer-affected children (<21 yr) expected to receive chemotherapy for at least 6 months and 53 age-and-ethnicity-matched controls. Analysis showed participants were 8.6 ± 5.2 yr, with BMI of 19.1 ± 5.0 kg/m2. Most participants were male (63.6%) and Hispanic (52.5%). The cancer and control groups were comparable in terms of age, gender, ethnicity, BMI, and 25OHD at baseline (all p>0.05). Of note, a few cancer patients missed some of their planned draws due to COVID-19 related precautions. The level of 25OHD did not differ between the cancer and control groups at T1, with or without controlling for age, gender, BMI, and season of measurement (both p > 0.05). The 25OHD level among patients with cancer was significantly different for different seasons (p = 0.0047). Levels of 25OHD significantly increased over time among children with cancer (p = 0.0040). However, when patients' age, gender, ethnicity, BMI, and season were controlled for, it was found that the 25OHD level did not change over time (p = 0.1817). Among the cancer patients, the concentrations of 25OHD did not significantly correlate with the number of fever episodes and fever severity scores (all p>0.05). Conclusion: 25OHD levels were not lower in patients with cancer compared to their matched controls even when adjusting for variables associated with vitamin D deficiency. When controlling for these variables, the levels of 25OHD did not change significantly over time in children with cancer. Finally, lower 25OHD did not correlate with a higher incidence of fever or higher fever score, as a surrogate marker for infectious disease. Our findings dispute previous studies suggesting that children with cancer are at higher risk of vitamin D deficiency and that lower levels of vitamin D correlate with incidence or severity of infectious disease, when using fever as a surrogate marker. Larger studies are needed to better understand the role of vitamin D status in children with cancer.