Potential diagnostic role of circulating MiRNAs in breast cancer: Implications on clinicopathological characters

Circulating miRNAs are stable in body fluids and resembles their levels in cancer tissue/cells. They have been expressed in many cancers among them is breast cancer. Authors aimed to investigate the expression levels of three circulating oncomiRNAs (miRNA-21, miRNA-222 and miRNA-373) in serum samples as a minimally non-invasive method for early detection of breast cancer, and study their relation with clinicopathological characters.

MiRNAs expression levels were determined using quantitative real-time polymerase chain reaction (qPCR) in serum samples from three groups: primary breast cancer patients (n = 137), benign breast lesion patients (n = 60), and healthy individuals as control group (n = 38). Statistical analyses were carried out using SPSS.

Significant differences were observed between the expression levels of the studied miRNAs in the investigated groups, as their median levels were increased in breast cancer patients followed by benign group patients then the healthy individuals. MiRNA-373 reported the highest diagnostic efficacy as compared to miRNA-21 and miRNA-222 with high area under the curve (AUC equals 0.987). The relation between tested miRNAs and clinicopathological factors revealed significant difference with clinical stages and histological grades. Level of miRNA-21 and miRNA-373 were statistically significantly higher in invasive duct carcinoma (IDC) as compared to non-IDC. Similarly, their levels were increased in lymph node metastasis (P < 0.01). MiRNA-222 and miRNA-373 were significantly increased in positive PgR and positive Her-2/neu status, respectively.

Assessment of miRNAs in serum samples can be applied as minimally non-invasive markers for early detection of breast cancer, and as discriminator between different clinicopathological characters.