The aim of the projects in this thesis was to identify biomarkers for clear cell renal cell carcinomas (ccRCC) and head and neck/oral squamous cell carcinoma (HNOSCC), using quantitative or qualitative proteomics. Comparative analysis of cancerous and normal tissue homogenates, or secretome analysis of cancer cell cultures using liquid chromatography - mass spectrometry (LC-MS) and immunoassay techniques, allowed the identification of different types of biomarkers: diagnostic or prognostic, biofluid- or tissue-based. Chapter 1 of this thesis provides general information on cancer and cancer biomarker discovery. Chapter 2 gives a brief introduction to the techniques used in this work and theories behind them. Chapters 3 - 5 are papers that resulted from the cancer biomarker discovery research performed here, and Chapter 6 contains the conclusions, the author's comments and the final remarks. The papers on the identification of biomarkers for different diseases, to which the author of this thesis contributed, are listed in the Appendix
