Cancer: eavesdropping on communicating cancer cells Cancer cells routinely release tiny membrane vesicles laden with RNAs that help promote tumor progression, but which could also offer useful biomarkers for diagnosis and reveal new drug targets. Many cells secrete such vesicles, known as exosomes, as a mode of intercellular communication. Researchers led by Tongbao Feng at Nanjing Medical University, Changzhou, China, have reviewed the evidence linking exosome-borne RNAs to tumor cell function. The authors focus on a class of molecules known as 'long noncoding RNAs' (lncRNAs), and show that exosomal lncRNAs are relayed as messages between tumor cells, promoting proliferation, metastatic spread, and acquisition of drug resistance. These RNAs can therefore also offer a useful window into the progress of disease and interventions that block such exosomally transmitted messages, and could potentially inhibit malignant growth and spread. Exosomes play a vital role in cell-cell communication within the cancer microenvironment. Exosomal long noncoding RNAs (lncRNAs) are important regulators in cancer development and are involved in multiple processes, including cancer cell proliferation, angiogenesis, metastasis, drug resistance, and immunomodulation. Changes in the levels of exosomal lncRNAs often appear with the occurrence and development of cancer. Therefore, exosomal lncRNAs can be used as biomarkers for cancer diagnosis and prognosis. Exosomal lncRNAs can also indicate the treatment response of patients receiving chemotherapy. Moreover, exosomal lncRNAs are potential therapeutic targets for cancer treatment. In this review, we summarize the role of exosomal lncRNAs in cancer biology as well as in clinical management. A more comprehensive and in-depth understanding of the role of exosomal lncRNAs in cancer may help us better understand the mechanism of cancer development and clinically manage cancer patients.