Liquid biopsy in cutaneous oncology: Current practice and future directions.

Over the past decade, the development and implementation of novel circulating tumor "liquid biopsies" in clinical practice has revolutionized cancer care. These tools provide sensitive and specific analysis of tumor status which enable non-invasive alternatives to tissue biopsy for real-time tumor monitoring, guided targeted therapy, predicted treatment response, and assessing therapeutic resistance and residual disease. The FDA has already approved several assays to detect genetic alterations in plasma cell-free DNA for use as companion diagnostics matched to specific molecularly targeted therapies for cancer, setting the stage for future use in early relapse detection and additional applications which are expected to be incorporated into standard-of-care practices for aggressive cutaneous malignancies. It will therefore be important for the dermatology community to have a working knowledge of liquid biopsy techniques and their relevance to the management of cutaneous malignancies. This review highlights state-of-the-art liquid biopsy tools currently in practice with an emphasis on the development and implementation of circulating biomarkers in skin cancers. It is anticipated that liquid biopsy tools will soon become integrated into evolving standards-of-care for improved management of patients with aggressive cutaneous malignancies.