Cancer stem cells: Current concepts, therapeutic implications and challenges

An increasing number of studies support the concept that cancer stem cells (CSCs) are responsible for initiation, growth and metastasis of malignant neoplasms. CSCs represent the population with tumor initiating potential, and possess the properties of normal stem cells, including the ability of self-renewal and perpetual proliferation, as well as the specific potential of multilineage differentiation, which underlies tumor heterogeneity. The persistence of CSCs has been considered the main culprit for tumor relapse and metastasis, since conventional oncologic protocols do not eradicate CSCs. Development of specific therapeutic strategies targeting CSCs may contribute to significant advance in cancer treatment. The crucial step in CSC targeted therapy development, as well as in subsequent efficacy validation, is the identification of specific stem cell markers, where the role of pathologist is of major significance.