Clinical aspects of circulating miRNA-335 in breast cancer patients: A prospective study

Background: The impact of aberrant expression of miRNAs, small noncoding RNAs of 19 to 23 nucleotide, has been reported in different types of cancer, such as breast cancer. Authors aim to investigate the role of circulating miRNA-335 as a diagnostic and prognostic marker for breast cancer. Materials and Methods: miRNA-335 expression was measured in primary breast cancer patients (n = 106), patients with benign breast lesion (n = 49) and healthy individuals as control (n = 40) using quantitative real-time polymerase chain reaction and its diagnostic efficacy, relation with clinicopathological factors, and disease-free survival (DFS) and overall survival (OS) were assessed. Results: A significant decrease in miRNA-335 expression was reported in patients with breast cancer as compared to the other two investigated groups. The positivity rate for miRNA were related to adverse clinical features of primary breast cancer as high histological grading (X 2 = 7.72, P = 0.016), presence of metastasis to lymph node (X 2 = 21.8, P < 0.001), large tumor size (X 2 = 6.41, P = 0.041), and hormonal status (P < 0.001). miRNA-335 mean rank level was significantly different among breast cancer subtypes and its level was inferior in triple negative breast cancer. Worse DFS (X 2 = 7.76, P = 0.005) and OS (X 2 = 9.3, P = 0.002) were reported with decreased miRNA-335 level. Conclusion: Assessment of circulating miRNA expression level is a promising minimal invasive marker for diagnosis and prediction of breast cancer prognosis with significant discrepancies among molecular breast cancer subtypes.