Background and purpose: MicroRNAs (miRNAs

miR) are directly involved in cancer initiation

progression and metastasis. Alterations of miRNAs expression in cancer tissue may be reflected in circulation. We attempted to investigate the expression and clinical significance of plasma miR-221 in patients with small cell lung cancer (SCLC). The plasma and tissues levels of miR-221 in 51 SCLC patients and 20 controls were evaluated and compared among various clinicopathological characteristics. Methods: Confirmation of higher miR-221 levels in primary SCLC tissues than normal lung tissues. Evaluation of plasma miR-221 concentrations by comparing results from 51 consecutive SCLC patients and 20 healthy volunteers. Evaluation of the assay for monitoring tumour dynamics in SCLC patients. Results: Expression of miR-221 was significantly higher in SCLC tissues than in para-carcinoma tissues and normal lung tissues. Plasma miR-221 concentrations were significantly higher in SCLC patients than those in normal people (P0.05). The expression of plasma miR-221 was not associated with gender

and age (P0.05)

correlated with significantly chemosensitivity

overall survival and clinical stage (P0.05). Cox regression analysis indicated that plasma miR-221 expression and disease stage were found to be significantly independent prognostic factors for the SCLC patients. Conclusion: Plasma miR-221 could be a useful biomarker for cancer detection

monitoring tumour dynamics and predicting malignant outcomes in SCLC patients

and may contribute to clinical decision making in treatments.