Circulating U2 small nuclear RNA fragments as a diagnostic and prognostic biomarker in lung cancer patients

Lung cancer accounts for one in five cancer deaths. Broad screening strategies for high-risk populations are unavailable, and the validation of biomarkers for early cancer detection remains a prime interest. Therefore, we investigated the value of circulating U2 small nuclear RNA fragments (RNU2-1f) as a biomarker for diagnosis, prognosis estimation and treatment monitoring in a large lung cancer cohort. We determined RNU2-1f abundance in sera of patients with treatment-naive lung cancer (n = 211, 25.6 % early stage), chronic lung disease (n = 56) and healthy controls (n = 58) by reverse transcription quantitative PCR. Initial levels and changes after one chemotherapy cycle were correlated with treatment outcomes in patient subsets. Relative serum RNU2-1f expression levels (REL) were elevated in lung cancer patients compared with patients with chronic lung disease and healthy controls (p