In a wide spectrum of tumors, cell proliferation, vascularity, apoptosis, cell adhesion, and cell-cycle progression may indicate tumor progression. In this review article, the literature regarding apoptotic markers and p53, as well as cyclooxygenase-2, galectin-3, and pituitary tumor-transforming factor, proliferative markers, angiogenesis, including vascular endothelial growth factor and its receptor, pituitary tumor-transforming gene, microarrays, stem cells, and microenvironment and tumor heterogeneity are presented. Only a particular group of selected biomarkers show promise in differentiating pituitary tumors which will behave in an aggressive manner. Therefore, the most common and promising biomarkers and terms were analyzed, proposing the need for uniform design and application of methods and standardized criteria for the interpretation of results. The new spectrum of biomarkers may shed light upon the pathogenetic mechanisms and also may serve as standardized diagnostic tool for daily pathologic practice.