Comparaison des altérations microsatellitaires dans une population de cancer du sein avant et après traitement par chimiothérapie première: Microsatellites alterations before and after primary chemotherapy in locally advanced breast cancers

Abstract

Breast cancer is characterized by a great genetic instability with a frequent presence of LOH (Loss of heterozygosity) or sometimes MSI (Microsatellite Instability). In order to determine the role of genetic instability in relation to response to chemotherapy, we analysed 84 locally advanced breast carcinomas treated with adriamycin-based primary chemotherapy regimen. Twelve microsatellites were analysed using a polymerase chain reaction-based method and capillary electrophoresis (Abi Prism 310-Applied Biosystems-). Our results show that before treatment, 15% of LOH are found particularly on 17p13.1, 3p24 and Xq13 (androgen receptors). A decreased of LOH number (5%) was observed for all microsatelittes after treatment. A significant relationship is shown between the presence of LOH at 11p15.5 and 3p21.1-14.2 loci and clinical parameters: poor therapy response ( P=0,0087) and death ( P=0,041) for the first locus, recurrence ( P=0,04) and death ( P=0,012) for the second. So, these alterations may be considered as prognostic factors for chemotherapy response in breast cancers. Further studies are under investigations with additional cases and microsatellites markers to confirm these results.