Breast cancer, lung cancer, and liver cancer are explored in the highest number of cancer biomarkers-related documents (Figure ). Noteworthy, when normalized over the all documents related to the specific cancer type, the value is the highest for the pancreatic cancer biomarkers, i.e., from all pancreatic cancer-related documents, the highest number are also associated with biomarkers, as compared to other cancer types (Figure , orange line); this normalized number of documents value is similarly high for the ovarian cancer biomarkers (Figure , orange line). With respect to annual growth, all major cancer types mark substantial growth in the recent three-year period, but lymph node cancer, pancreatic cancer, and liver cancer are those drawing attention with an especially steady growth in the number of recent publications (Figure ). Cancer biomarkers belong to a variety of molecular types and structures including proteins, nucleic acids, cellular metabolites, also exosomes, and various other organic materials and tissues. Protein biomarkers have been among the first and the most widely used in cancer diagnostics. Most of them are based on cancer antibodies / immunoglobulins, enzymes, and hormones, as reflected by the number of published documents (Figure ). Protein biomarkers include overexpressed proteins (e.g., HER2), mutated proteins (e.g., p53), or proteins with tumor-specific post-translational modifications (e.g., KRAS mutations), which can be found in tumor tissue. Protein biomarkers detectable in blood or other body fluids also include tissue/cell-specific proteins that have enhanced levels in body fluids as compared to normal, e.g., PSA in the blood plasma of prostate cancer patients. Proteome characterization in cancer has been recently assessed by two initiatives, the Clinical Proteomic Tumor Analysis Consortium 111 and the Human Protein Atlas 112 .