Prospective Analysis of Serum Zinc and Selenium Levels in Children with Cancer

Serum zinc and selenium concentrations might be altered by various disease conditions including malignancies. We aimed to prospectively investigate the serum levels of both elements in pediatric cancers. Children <18 years with newly diagnosed cancers were eligible. Data regarding demographics, histopathological diagnoses, tumor sites, disease extent, treatments given and outcomes were recorded. Serum samples were obtained at diagnosis and in the 3-4 months after diagnosis to determine the serum concentrations of zinc and selenium using "inductively coupled plasma mass spectrometry" (ICP-MS) method. Serum levels were compared to normal references and also in the subgroups according to tumor types, tumor sites and disease extent. Eighty-one children were included (Male/female: 50/31, median age 7.5-years). Twenty-five patients had lymphomas and 56 had solid tumors. For all patients, median serum levels of zinc and selenium were 69.5 mcg/dL and 114.3 mcg/L, respectively, which were comparable to normal reference values. In patients with lymphomas, mean and median initial zinc levels were significantly lower compared to solid tumors, which increased following treatment. No significant difference was detected in initial selenium concentrations of all patients and also in the subgroups. In the 3.-4. months following treatment, selenium levels decreased significantly in solid tumors. No significant difference was detected in the survival rates according to Zn and Se levels. Lower zinc levels at diagnosis in lymphomas was remarkable. The decline in Se levels after treatment may reflect the selenophilic nature of solid tumors and could also be linked to reduced appetite and dietary intake. Suppression of hepatic biosynthesis of selenoprotein by some chemotherapeutics might also contribute to diminished selenium levels after treatment. Further studies are needed to explore the implications of deficiencies in both elements.