Abstract
BACKGROUND: Although histopathological examination of the biopsy specimen is the gold standard for the diagnosis of non small cell lung cancer (NSCLC), a blood-based noninvasive test (liquid biopsy) may prove to be helpful in patients with repeatedly negative biopsy or for response assessment following neoadjuvant therapy. The present study was conducted to explore the diagnostic value of circulating serum microRNA (miRNA) 21 in patients with NSCLC. METHODS: This case-control analytical study was carried out in a tertiary care teaching hospital in Northern India. The study consisted of 30 cases of biopsy-proven NSCLC and 30 controls. Serum miRNA-21 expression levels were estimated by extracting total RNA from the serum sample, reverse transcribing it to cDNA and quantified in relation to U6 reference miRNA. RESULTS: A total of 30 patients with NSCLC and 30 controls were included in the study. The subjects were comparable in two groups with reference to age, gender, and smoking. Pathological types were adenocarcinoma in 19 (63.3%) and squamous cell carcinoma in 11 (36.6%) patients. Majority of the patients had advanced disease-AJCC stage III in 15 patients and AJCC Stage IV in 13 patients; two patients had stage II disease. There was a significant upregulation of serum miRNA 21 gene expression in the patients with lung cancer compared to controls (median fold change, 3.39 vs. -2.81, P = 0.00). A fourfold change in serum miRNA 21 is significantly associated with the diagnosis of NSCLC with a high specificity of 97% and area under curve of 0.84 (95% confidence interval of 0.74-0.94). CONCLUSION: Estimation of serum miRNA 21 expression has potential to be used as liquid biopsy for the diagnosis of NSCLC. Further studies with large sample sizes are warranted to confirm the diagnostic accuracy of serum miRNA 21 expression.