Nowadays much attention is paid to non-invasive methods of cancer diagnostics and monitoring. One of the promising methods is the sequencing of platelet RNA (tumor-educated platelets), in which, as it was previously established, the mRNA repertoire changes in various oncological diseases. Thus, platelets can contain information about the molecular genetic characteristics of tumor. This review summarizes the current understanding of the mechanisms of interaction between tumor cells and platelets, and also discusses the possibilities of using platelet transcriptome analysis methods for diagnosing and assessing the dynamics of the tumor state, in particular, in response to therapy, as well as the current limitations for a wide range of introduction of this method into clinical practice.