Advances in liquid biopsy for bone and soft-tissue sarcomas

Bone and soft-tissue sarcomas are a heterogeneous group of malignant tumors originating from mesenchymal tissues, accounting for approximately 1% of adult solid malignancies and 20% of pediatric solid malignancies. While blood-based tumor markers are available in major types of cancers, evidence demonstrating useful circulating biomarkers is limited in bone and soft-tissue sarcomas. Despite the development of combined modality treatments, a significant proportion of sarcoma patients respond poorly to chemotherapy or radiotherapy, leading to local relapse or distant metastasis. However, imaging methods, such as X-ray, computed tomography, positron emission tomography, magnetic resonance imaging, and scintigraphy, are mostly used to detect or monitor tumor development. Liquid biopsy is an emerging minimally invasive diagnostic technique that detects tumor-derived molecules in body fluids, including circulating tumor cells, circulating tumor DNA (ctDNA), circulating tumor RNA (ctRNA), and circulating extracellular vesicles. This method offers new possibilities for early tumor detection, prognostic evaluation, and therapeutic monitoring and may serve as a benchmark for treatment modification. This review focuses on the current technological advances in liquid biopsy for bone and soft-tissue sarcoma and explores its potential role in guiding personalized treatments. If these modalities could determine resistance to ongoing therapy or the presence of minimal residual disease at the end of the treatment protocol, the obtained data would be important for determining whether to change treatment approaches or add adjuvant therapies.