Cancer biomarkers (CB) are biomolecules produced either by the tumor cells or by other cells of the body in response to the tumor. Every cell type has its unique molecular signature and identifiable characteristics such as levels or activities of myriad of genes, proteins, or other molecular features; therefore, biomarkers can facilitate the molecular definition of cancer. Our aim was providing updated knowledge and performing detailed review about CB regarding their molecular and biochemical characterization and their clinical utility in screening, diagnosis, follow-up, or therapeutic stratification for cancer patients. Focusing on conventional, the FDA approved as well as promising future biomarkers in most common cancers. In addition, emphasizing on their prospective role may be of great value in improving the management of cancer patients. The challenge and future prospective of biomarkers, by facilitating the combination of therapeutics with diagnostics, promise to play an important role in the development of personalized medicine.

Substantial progress has been made over the past three decades in understanding breast cancer (BC) molecular biology, genomics, and targeted therapy. The recent comprehensive molecular and pathological diversity observed in BC patients indicates that BC is not a homogeneous disease; It may be appropriately defined as a myriad of diseases. The explosion of molecular information in the past 10 years has led to a better understanding of the biologic diversity of breast cancers (BCs), and clues to the different etiologic pathways to BC development. It will be useful to study the epigenetics of BC cells and define the mechanisms of both genetic and epigenetic driving alterations beside the mutations. Identifying the oncogenes and tumor suppressor genes is the purpose cancer diagnostics and therapeutics. Oncogenes as well as novel ones involved in the significantly altered regions would enable researchers to identify new causes and molecular pathways that may be targeted at BC treatment. Our main goal is to provide comprehensive understanding of underlying molecular mechanisms and hallmarks of BC, focusing on the identification of fingerprints and novel molecular targets that will greatly improve the cancer predictive, prognostic, and diagnostic biomarkers and, in addition, the possible targets for novel therapies.