Background:
Lung cancer is one of the leading causes of mortality in the world. The main reason for poor lung cancer prognosis is that the patients are often diagnosed in late stages with advanced disease. The expression of some miRNAs has been reported to be involved in diagnosis, classification and prognosis of lung cancer. This study aimed to evaluate the role of plasma miRNA 155 and miRNA 197 in lung cancer.
Subjects and methods:
This study included sixty lung cancer patients and twenty apparently healthy individuals. Complete blood picture, kidney and liver function tests, serum glucose, lactate dehydrogenase, and carcinoembryonic antigen (CEA) were done by standard methods. Plasma miRNA 155 and miRNA 197 were done by Real-time polymerase chain reaction.
Results:
There were significant elevations in serum CEA and plasma miRNA155 and miRNA197 in lung cancer patients compared to control group. miRNA155 and miRNA197 showed significant elevation with advanced tumor stage and metastasis. CEA at cutoff (28 ng/ml) resulted in 74% sensitivity. MiRNA 155 at cutoff (152 fold changes) resulted in 93% sensitivity. MiRNA 197 at cutoff (159.18 fold changes) resulted in 90% sensitivity. The specificity was 100% for all. Combined use of miRNA155, miRNA197 and CEA increased the sensitivity to 94.8%.

Conclusion:
Plasma miRNA 155 and miRNA197 are more sensitive than CEA as tumor markers for lung cancer. They are correlated with tumor stage and presence of metastasis but not correlated with histological types.