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Thoracic cancers are the leading causes of cancer-related deaths worldwide. Recent advances in genome and transcriptome analysis have allowed for the identification of numerous classes of noncoding RNAs (ncRNAs) that play important roles either in a biological process or human disease. microRNAs (miRNAs) are small, 19–22 nucleotides, ncRNAs that regulate posttranscriptional gene expression by binding to the 3' untranslated region (3'UTR) of their target mRNA. Conversely, long noncoding RNAs (lncRNAs) are a novel class of transcripts longer than 200 nucleotides that do not encode any proteins. Some lncRNAs can interact with miRNAs and act as repressors, impeding them to bind to their protein-coding targets. There is cumulative evidence that these ncRNAs contribute to the tumorigenic process regulating cell growth, apoptosis, and metastasis, and may serve as biomarkers in various types of tumors. In this review, we have summarized the important role of ncRNAs as promising biomarkers in liquid biopsy for the diagnosis and prognosis of thoracic malignancies such as lung cancer, mesothelioma, and thymoma.

Lung cancer is the most common malignancy in the United States, totaling 225,000 cases per year. In recent years, several new treatment options have become available based on the molecular and cellular characterization of the disease. More recently, "liquid biopsies" have received attention to complement traditional tissue biopsies and to enhance the spectrum of analysis for tumor-derived factors. As one of these tumor characteristics, extracellular vesicles (EVs) are lipid bilayered EVs that can cargo a variety of factors, including growth factors and their receptors, RNA transcripts, microRNAs, and DNA, among others. Initial acceptance as mere physiological products has been attributed to the presence of exosomes in healthy individuals, and the large diversity of exosomes that have made the assignment of distinct pathophysiological roles difficult. While their role in clinical application has not yet been established, they have emerged from their once thought innocent role as a bystander to a critical mediator of intratumoral signaling, tumor progression, chemotherapy resistance, and metastasis. In this review, we have summarized the structure and biology of EVs, their role in lung cancer, and the potential diagnostic and therapeutic implications for the treatment of this complex disease.