This Special Issue is lead by Prof. Ales Ryska, President Elect of the European Society of Pathology. Prof. Ryska's research interests focus on the diagnostics of lesions of the breast, thyroid and salivary glands - cytology, histology and special methods, such as immunohistochemistry and molecular biology.

The current development of our understanding of tumor biology, role of individual driver mutations and activation of signaling pathways is reflected in rapid implementation of targeted therapy of tumors. To identify patients, who are the best candidates of such treatment, requires use of up-to-date molecular testing of tumor tissue. However, use of molecular techniques is sometimes precluded by limited tissue specimens (insufficient neoplastic cell content, poor quality of nucleic acids, etc.). For the last 10 years, so-called liquid biopsy - testing of cell free tumor DNA or circulating tumor cells isolated from the patients' blood - has been demonstrated as a feasible alternative solution. This approach shows many additional promising applications, such as control of minimal residual disease, early detection of tumor recurrence or detection of development of resistant clones. This resulted in huge clinical expectations which, however, cannot be always fulfilled.

So, what is the current position of liquid biopsy in routine clinical practice? Is it a real game changer or rather a highly sophisticated laboratory test with limited clinical use?

This special issue is focused on opinions from experts in this field, who will share their experience, critical view and scientific results clarifying the role of liquid biopsy in modern oncology. You can expect, among others, review articles from world renowned experts H. Popper or A. Khoor.

For authors, please also review the journal's information regarding Author Guidelines and Article Processing Charges, or direct any questions to the Editorial Office: por@por-journal.com.

Keywords: liquid biopsy, cell-free DNA, ctDNA, circulating tumor cells, tumor heterogeneity, minimal residual disease, predictive pathology, targeted therapy