Micro-Rnas As Positive Biomarkers Of Pathological Complete Response After Neoadjuvant Chemoradiotherapy In Locally Advanced Rectal Carcinoma.

624 Background: Neoadjuvant chemoradiotherapy (nCRT) follow by surgery, as treatment for locally advanced rectal carcinoma (LARC), has improve local disease control, increase of complete pathological response (cPR) and preserve anal sphincter. cPR is associated with better prognosis. CRT act mainly through induction of DNA damage. MicroRNAs (miRNAs) are small non-coding RNAs able to regulate gene expression at post-transcriptional level. miRNAs are involved in the regulation of DNA damage/repair mechanism. Our goal was to measure expression of miRNAs involved in DNA damage/repair genes and correlated with cPR. Methods: Retrospectively, we analyzed the initial paraffin embedded tissue block of 20 Mexican patients with LARC treated with nCRT at National Cancer Institute of Mexico between 2010-2013. Treatment response was evaluated with Ryan Classification. Ten patients had cPR (Ryan Grade 0) meanwhile other 10 poor response (Ryan Grade 3). RNA extraction was done with RNeasy FFPE (Qiagen) Kit. RNA concentra...