Tissue-Based and Liquid Biopsy Testing in HR+/HER2-Negative Advanced Breast Cancer

Dr. Paolo Tarantino discusses the role of molecular testing in patients with hormone receptor-positive, HER2-negative metastatic breast cancer, outlining two approaches for characterizing the tumor's molecular landscape: tissue-based testing and plasma-based testing. He explains that tissue-based testing typically involves obtaining a tumor biopsy for next-generation sequencing (NGS), whereas liquid biopsy uses a blood sample to assess circulating tumor DNA (ctDNA). He highlights the less invasive nature of liquid biopsy and its potential to capture a broader representation of tumor heterogeneity over time and across different disease sites. In contrast, a tissue biopsy provides molecular information from the specific tumor site sampled. Dr. Tarantino notes that liquid biopsy is often a more convenient approach for patients whose disease has progressed following CDK4/6 inhibitor-based therapy. However, when tumor tissue is readily accessible, he suggests that both approaches may be considered in selected cases to help characterize the disease.