Author Proof 1 ISSN 1758-4299 10.2217/CLP.12.79 © 2013 Future Medicine Ltd Clin. Lipidol. (2013) 8(1), 1–xxx REVIEW Cancer biomarkers and mass spectrometry-based analyses of phospholipids in body fluids Lipidomics is a field within molecular biology that focuses on the global composition and dynamic changes of lipids and their derivatives in biological systems such as cells and tissues [1] . Although lipidomics is a direct subset of the field of metabolomics, due to the uniqueness and functional specificity of lipids relative to other metabolites, lipidomics is itself a distinct discipline. Among different biomaterials, body fluids are the primary focus in lipidomics. Blood serum and plasma are the most frequently used materials for clinical diagnostics as they constitute the most complete mixture of all kinds of metabolites and proteins; however, urine, ascitic fluid, saliva, bronchial washes, prostatic secretions or fecal water samples are also used for biomedical purposes. The choice of analytic technique used in lipidomics depends mainly on the sample type (various biofluids vs tissues). Due to recent developments, the most promising methods used for lipid analyses of biofluids are mass spectrometry (MS) [2,3] and, to some extent, nuclear magnetic resonance spectroscopy [4] . Undoubtedly, the main advantages of MS over traditional methods (e.g., only chromatography) are high throughput, low cost (in comparison with nuclear magnetic resonance), better sensitivity and selectivity, short analysis times, and small initial sample volume. Apart from the identification of phospholipid class, MS methods are also able to deliver very precise information, such as the length [5] and location [6] of double bonds within fatty acid residues. For the analysis of lipids in solid tissues, MS imaging (MSI) is successfully applied [7] . Due to the unique metabolic phenotype of malignant cells, lipidomics is an emerging approach in the field of cancer research. Potential applications of cancer lipidomics include detection and classification of tumor cells, and determining prognosis, as well as monitoring and evaluating the effects of anticancer treatment. This review focuses on the application of MS-based analysis of body fluid phospholipids in cancer research. Phospholipids in cancer Phospholipids (PLs) are major components of cell membranes, which are involved in the progression and metastasis of cancer when tumor cells undergo major morphological and molecular changes. In mammalian cells, membrane lipids consist mainly of sterols (mostly cholesterol) and glycerol-based phospholipids [8] . Phosphatidic acid (PA) is the simplest glycerophospholipid, which is composed of diacylglycerol and a phosphate group. In the majority of glycerophospholipids, the phosphate group is estrificated with a polar alcohol group, The lipid profiles of body fluids reflect the general condition of the whole organism and can indicate the existence of certain diseases such as cancer. Qualitative and quantitative assessment of lipids in blood and other body fluids could reveal novel biomarkers for early detection and prognosis of cancer; in addition, it may be useful in monitoring the efficacy and toxicity of anticancer treatment. Consequently, lipidomics is an emerging approach in cancer research. Phospholipids make up an important lipid class, which is particularly suitable for analyses by mass spectrometry. Mass spectrometry methods involving ‘soft’ ionization techniques, such as electrospray ionization and matrix-assisted laser desorption ionization, which are well established in the proteomics field, have also been implemented in analyses of lipids. This review focuses on the application of electrospray ionization and matrix-assisted laser desorption ionization mass spectrometry in the characterization of structure and composition of phospholipids present in biofluids, and their importance for cancer-related problems. KEYWORDS: biofluid n cancer biomarker n lipidomic n mass spectrometry n phospholipid Karol Jelonek* 1,2 , Malgorzata Ros 1,2 , Monika Pietrowska 1 & Piotr Widlak 1 1 Maria Sklodowska-Curie Memorial Cancer Center & Institute of Oncology, Gliwice, Poland 2 Polish–Japanese Institute of Information Technology, Bytom, Poland *Author for correspondence: Tel.: +48 32 278 9628 Fax: +48 32 278 9808 kjelonek@io.gliwice.pl part of