Every year, millions of people around the world lose their lives to different types of cancer, mostly in developing countries. The foremost challenge for the human race in to fight against cancer is its early detection, followed by the appropriate treatment. Currently, one of the most promising and dynamic strategies for early cancer diagnostics as well as for therapeutics, is the use of cancer biomarkers. Generally, biomarkers represent changes in the constituents or composition of cells, tissues, or body fluids, offering a means for comparable classification of diseases as well as the risk factor involved, and thereby providing information about the underlying pathogenesis of the disease. Similarly, a cancer biomarker (CB) is defined as a ‘molecular signature’ that can potentially provide valid information regarding staging as well as the mechanisms underlying the origin of cancer. Cancer biomarkers (CB) are biomolecules synthesized either by the cancer cells or by other cells of the body in response to cancer. Every cell type has its distinctive molecular signature and recognizable features, such as levels or activities of the myriad of genes, proteins, or other molecular characteristics; therefore, cancer biomarkers can facilitate the molecular definition of cancer. Endoscopy, X-rays, magnetic resonance imaging, computed tomography, invasive tissue biopsies, etc., are the traditional cancer diagnostic methods. However, the use of biomarkers as cancer screening tools have several advantages over these traditional approaches. The emergence of “omics” technologies, like metabolomics, genomics, epigenomics, proteomics, etc., has led to an increase in the number of potentially investigated biomarkers, such as DNA, RNA, miRNA, or other protein biomolecules. In this chapter, we have summarized the importance of biomarkers as powerful and dynamic tools for the early diagnosis of various types of cancers, the phases in the biomarker discovery, the criteria for the selection of biomarkers, the advantages of their preference over traditional methods, various categories of cancer biomarkers, examples of cancer biomarkers currently in use and the future prospectives.
Keywords: Biomarkers, Cancer, Circulating tumor cells, Diagnosis, Exosomes, Metastasis, MiRNA, Prognosis, Specificity.
