MiR-640 and MiR-525-5p as Relapse-Associated MicroRNAs in Systematically Untreated Individuals with Low-Risk Primary...

MicroRNAs have been suggested to be signatures for predicting recurrence in breast cancer. This study aimed to identify miR-640 and miR-525-5p as relapse-associated microRNAs in systematically untreated and lymph node negative patients with primary breast cancer. GEO datasets GSE126125 and GSE103161 were analyzed to find the differential microRNAs in primary breast cancer with and without relapse. Systematically untreated patients (n = 180) with low-risk primary breast cancer were selected in this independent validation set, and 48 patients developed relapse within 5 years. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was used to detect miR-640 and miR-525-5p expressions in tumor tissues. Based on the retrieved data from GSE126125, miR-640 and miR-525-5p expressions were significantly lower in tumors from patients with relapse compared to tumors from patients without relapse, accompanying by highly predictive potential to discriminate cases with and without relapse. The decreased miR-640 and miR-525-5p expressions were revealed in dead patients as compared to alive patients. In the independent validation set, patients with low expression of miR-640 and miR-525-5p showed poor outcome as compared to those with high expression. The receiver operating characteristic (ROC) curves of miR-640 and miR-525-5p for evaluation as diagnostic markers were depicted with the area under curves (AUCs) of 0.940 and 0.886, respectively. Tumors with larger size and higher grade had lower expression of miR-640 and miR-525-5p. MiR-640, miR-525-5p and histologic grade were significant predictors of relapse-free survival (RFS). Our study validated the values of miR-640 and miR-525-5p in predicting relapse of systematically untreated and lymph node negative patients with primary breast cancer.