Current and future applications of liquid biopsy in non-small-cell lung cancer-a narrative review.

Background and Objective: Lung cancer remains the leading cause of cancer-related mortality and constitutes a significant societal burden. Recent advancements in targeted therapies and immunotherapy have considerably broadened therapeutic options in lung cancer, particularly in non-small-cell lung cancer (NSCLC). However, these novel methods necessitate sophisticated molecular diagnostics. Liquid biopsy, which refers to the cytological and molecular analysis of cancer markers shed by the tumor into the body fluids, may offer an attractive diagnostic tool at the individual patient level. This approach is particularly relevant for lung cancer, as the anatomical location of tumor lesions frequently makes them inaccessible for tissue biopsy. Apart from minimal invasiveness, the major advantages of liquid biopsy include better reflection of the tumor clonal heterogeneity (spatial heterogeneity), the possibility of sequential sampling, and real-time monitoring of tumor load and its evolving mutational status (temporal heterogeneity). Methods: This article reviews the available data in this field, current applications, and future perspectives in accordance with the Narrative Review reporting rules. Key Content and Findings: We discuss the most used approaches, i.e., circulating DNA and tumor cells, but also emerging liquid biopsy techniques, such as plasma DNA methylation, plasma metabolites and RNA, extracellular vesicles, and tumor-educated platelets in NSCLC. Finally, we highlight the current limitations of liquid biopsy techniques hampering their clinical applications. Conclusions: Due to their advantages, liquid biopsy-based approaches have recently gained immense interest in oncology. Potential applications of this method include early detection, informing precision medicine-based individualized treatment, and real-time monitoring of disease evolution and treatment. The development of next-generation sequencing has vastly extended genetic profiling, thus enabling better identification of druggable alterations. However, the clinical application of liquid biopsy techniques is still limited due to their suboptimal specificity and sensitivity, lack of standardization, and relatively high costs. Addressing these issues may allow further integration of liquid biopsies in the routine clinical setting, thus making a profound and permanent change in NSCLC management.