Ascertaining serum levels of trace elements in melanoma patients using PIXE and HR-ICPMS S. Bernardes a,⇑ , M.H. Tabacniks a , I.D.A.O. Santos b , A.F. Oliveira b , J.N. Shie b , J.E.S. Sarkis c , T. Oliveira c a Physics Institute, University of São Paulo, Brazil b São Paulo Federal University (UNIFESP), São Paulo, Brazil c Institute of Energy and Nuclear Research (IPEN), Laboratory of Chemical Characterization (LCQ), Center for Chemistry and the Environment (CQMA), São Paulo, Brazil article info Article history: Received 23 March 2013 Received in revised form 20 June 2013 Accepted 23 June 2013 Available online 17 August 2013 Keywords: Melanoma Trace elements Serum PIXE HR-ICPMS abstract Melanoma is a serious and deadly form of skin cancer. However, patients’ chances of survival and recov- ery are considerably increased when it is diagnosed and treated in its early stages. In this study, trace ele- ment concentrations in serum samples from patients with melanoma were measured using PIXE (Proton Induced X-ray Emission) and HR-ICPMS (High-Resolution Inductively Coupled Plasma Mass Spectrome- try), with the purpose of correlating these concentrations with the disease. Blood samples from 30 mel- anoma patients and 116 healthy donors were collected at São Paulo Hospital (protocol CEP 1036/08 UNIFESP). Relevant clinical information on the patients has also been included in the statistical analysis. Analysis of the control group showed different P and Mg concentrations in individuals above and below 40 years of age. P, S, Ca, Cu and Zn concentrations in healthy individuals differed according to gender, highlighting the necessity to include age and gender variables in the case-control analysis. There were also differences in K, S, Ca and Se concentrations between the control and melanoma groups. Ó 2013 Published by Elsevier B.V. 1. Introduction Bio-essential trace elements play a fundamental role in several biological or physiological functions. It is already well-known that various organic functions depend on concentration levels of several elements contained in cells or organs [1]. It is also known that alterations in the concentration of major elements in organic tis- sues and fluids can be linked to several diseases and can be used to evaluate the clinical picture of individuals, providing important data for the diagnosis of clinical disorders and intoxications [2–4]. It is also recognized that many elements may either be beneficial or harmful, depending on their concentration levels [5]. Further- more, individual factors such as gender, age, place of residence and nutritional habits also influence the levels of these elements and must therefore be taken into account and, if possible, filtered out for a reliable diagnosis [6]. Some studies have also established a link between trace elements and cancer [4,7–10,11,14]. Melanoma is one of the most aggressive forms of cancer in hu- mans, since it is highly invasive and progresses quickly [15]. Its aggressiveness is characterized by the ability of melanoma cells to invade tissues and to metastasize. In recent decades, the rate of melanoma has risen sharply among the world’s population for reasons that are not entirely understood. It is known, however, that exposure to the sun and genetic factors are important precursors of melanoma [11–13]. In this study, concentrations of elements in serum samples from 30 melanoma patients and 116 healthy control donors living in the city of São Paulo, Brazil, were measured using PIXE and HR-ICPMS. The original objective of this study was to contribute to melanoma diagnosis and to search for correlations between trace element concentrations and melanoma, and/or the stage of the disease. 2. Materials and methods 2.1. Sample collection and storage A total of 30 patients with melanoma and 116 healthy control subjects were selected for this case-control study. Blood samples were collected at São Paulo Hospital in 6 ml BD Vacutainer tubes without any additives. The melanoma group samples were collected immediately prior medication and surgery and the control blood samples were taken from the blood bank. Serum was obtained by centrifugation at 4500 rpm for 15 min. After separation, the serum samples were frozen at À20 °C and stored until sample preparation for analysis. All material used was sterile and disposable. 2.2. Sample preparation The samples were prepared according to three different meth- ods: external elemental standard addition, with and without acid 0168-583X/$ - see front matter Ó 2013 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.nimb.2013.06.064 ⇑ Corresponding author. Tel.: +55 11 984907308. E-mail addresses: suene@if.usp.br, suenebernardes@yahoo.com.br (S. Bernardes). Nuclear Instruments and Methods in Physics Research B 318 (2014) 178–181 Contents lists available at ScienceDirect Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb