Abstract P5-10-11: Clinical significance of microRNA expression as a prognostic factor in early N+ breast cancer (BC)

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Abstract Background: microRNAs (miRNAs) are small noncoding RNA molecules that post-transcriptionally regulate gene expression. In the present study, we describe miRNA expression in early node-positive BC and identify a 8-miRNA score that could contribute to prognosis assessment. Methods: First, microarray analysis was performed using RNA samples extracted from primary breast cancer. The expression of miRNAs was analyzed by RT-qPCR using the TaqMan Arrays from Applied Biosystems. After a suitable normalization of the 677 miRNAs analyzed, 123 presented a good correlation between their levels of expression in frozen tissue and paraffin tissue. A supervised analysis was done in order to identify MIR that could predict relapse. Results: 172 patients with node-positive chemotherapy-treated early BC were included in the present study. The median age at diagnosis was (53.7) years, 128 cases (74.4%) had positive estrogen receptor, and 163 patients (94,7%) received adjuvant chemotherapy. After a median follow up of 8,1 years, 71p (41.2%) relapsed. Supervised analyses identified 8 microRNAs (has miR-30e, miR-30a, miR-21, miR-210, miR-93, miR-150, miR-99b, miR-572) associated with higher risk of relapse (5 year PFS 50% vs 90%, HR 3.75, 95% CI 2.27–6.19) and with estimated overall survival (median not reached, HR 4.51, 95% CI 2.36–8.61). Interestingly, miRNAs defined 2 prognostic groups (high and low risk) regardless of type of adjuvant chemotherapy (with or without anthracyclines) and histological subtype (luminal A, B or triple negative). Conclusions: This study suggests that miRNA expression could contribute to assess molecular prognosis of breast cancer and identifies clusters of miRNAs that could improve outcome prediction. A validation study in node-negative and triple negative disease is planned. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-10-11.

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