An update on sputum MicroRNAs in lung cancer diagnosis.

Lung cancer is one of the leading cause of cancer mortality in the world. It is well known that genetic damages could result in lung tumor genesis. Despite years of research, the survival rate of the patients has not been markedly improved. According to lack of high sensitivity and specificity in diagnostic tests, just about 15-20% of lung cancer cases are discovered prior to progression of the disease. In last decade, sputum biomarkers have been developed for early detection/diagnosis of lung cancer. MicroRNAs are a class of small endogenous noncoding RNAs, which act as post-transcriptional regulators. Some specific miRNAs can have multifunctions in lung development and their aberrant expression could induce lung tumor genesis. The differences in miRNAs between the normal and cancerous lung lead to emerging of a novel type of biomarkers, which can be helpful in screening of high risk individuals, diagnosis of lung cancer as well as its therapy.