Liquid biopsies in sarcoma clinical practice: where do we stand?

Sarcomas are rare tumors of bone and soft tissue with a mesenchymal origin. This uncommon type of cancer is marked by a high heterogeneity, consisting of over 70 subtypes. Because of this broad spectrum, their treatment requires a subtype-specific therapeutic approach. Tissue biopsy is currently the golden standard for sarcoma diagnosis, but it has its limitations. Over the recent years, methods to detect, characterize, and monitor cancer through liquid biopsy have evolved rapidly. The analysis of circulating biomarkers in peripheral blood, such as circulating tumor cells (CTC) or circulating tumor DNA (ctDNA), could provide real-time information on tumor genetics, disease state, and resistance mechanisms. Furthermore, it traces tumor evolution and can assess tumor heterogeneity. Although the first results in sarcomas are encouraging, there are technical challenges that need to be addressed for implementation in clinical practice. Here, we summarize current knowledge about liquid biopsies in sarcomas and elaborate on different strategies to integrate liquid biopsy into sarcoma clinical care.