Cancer represents one of the leading cause of morbidity and mortality worldwide, with approximately 14 million new cases every year and more than 8 million cancer related deaths. In men, lung cancer is the most frequently diagnosed cancer type, followed by the prostate, colorectal, and gastric cancer; in woman, the most frequent cancer is the breast cancer, followed by the colorectal, lung, cervical, and stomach cancer. During the second half of the twentieth century the efforts to evaluate the importance of the solid tumor cells present in the circulating blood have been made. Similarly, long time ago in 1948, extracellular nucleic acids (circulating free DNA) floating around in human blood plasma were discovered. Exosomes were disclosed as the last component of this "triumvirate" present in the blood and applicable for diagnostics. The exosomal cargo consists of bioactive molecules from donor cells that can be transferred to recipient cells and modulate their intracellular signaling. Thus, exosomes can provide autocrine (local signals between the same cell type), paracrine (local signals between different cell types), and endocrine (distant signals between any types of cells) type of signals.
Keywords: cancer; exosomes; immune system; surviving..