Lung cancer screening in high-risk subjects: early detection with LDCT and risk stratification using miRNA-based blood test

Lung cancer still remains a high mortality disease in the face of developments in diagnostic and therapeutic methods that occurred in the last 20 years. The analysis of the experiences from the first studies - in which chest X-ray (CXR) was adopted, associated or not with sputum cytology - has failed to show a reduction in lung cancer specific mortality. Subsequent screening studies that have introduced the use of low-dose computed tomography (LDCT) have revealed a large number of early-stage lung cancers, thus potentially curable; however, this has not allowed us to demonstrate a decrease in lung cancer-specific mortality. With the results of the American study National Lung Screening Trial (NLST), published in 2011, for the first time a lung cancer-specific mortality reduction by 20% thanks to the use of LDCT compared to RXT, was highlighted. However, a false positive rate of 96.4% was also described with an over-diagnosis that can be up to 78.9% for bronchioalveolar lung cancer. Due to the high sensitivity of LDCT, able to identify a non-calcified pulmonary nodule in one subject on two, it becomes necessary to avail instruments to more accurately identify suspicious nodules. Until some time ago, the possible use of lung tumour markers was not viable in view of the poor organ specificity. The study and development was, then, pushed to organ-and tissue-specific markers such as microRNA (miRNA), non-coding RNA sequences involved in many processes and expression of oncogenic activity of the microenvironment. The use of biomarkers such as circulating miRNA implemented in LDCT screening has highlighted a reduction of 5 times for the rate of false positives, going from 19.4% to 3.7%, with a sensitivity of 87%, a specificity of 81%, and a negative predictive value of 99%. The need to appropriately use the available resources commensurate with the disease to treat will push more and more towards the implementation of LDCT biomarkers based screenings, stable and easily reproducible, as circulating miRNAs, obviating to problems such as false positives, unnecessary procedures of invasive surgery for benign lesions, and optimizing the cost-benefit ratios. The development of new specific biomarkers appears to offer new promising prospects.