©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 7 (1): 177-183 (2008) Correlation of polymorphism C3435T of the MDR-1 gene and the response of primary chemotherapy in women with locally advanced breast cancer F.F.O. Rodrigues 1 , R.E. Santos 1 , M.B. Melo 2 , M.A.L.G. Silva 3 , A.L. Oliveira 1 , R.L. Rozenowicz 1 , L.B. Ulson 1 and T. Aoki 1 1 Departamento de Obstetrícia e Ginecologia, Santa Casa de São Paulo, Faculdade de Ciências Médicas, São Paulo, SP, Brasil 2 Laboratório de Medicina Molecular, Departamento de Ciências Fisiológicas, Santa Casa de São Paulo, Faculdade de Ciências Médicas, São Paulo, SP, Brasil 3 Departamento de Patologia, Santa Casa de São Paulo, Faculdade de Ciências Médicas, São Paulo, SP, Brasil Corresponding author: F.F.O. Rodrigues E-mail: foliveirarodrigues@uol.com.br Genet. Mol. Res. 7 (1): 177-183 (2008) Received November 15, 2007 Accepted December 27, 2007 Published February 19, 2008 ABSTRACT. Primary chemotherapy is a useful strategy for the treatment of locally advanced breast cancer and therefore allows in vivo evaluation of the action of cytotoxic drugs and the possi- bility of accomplishing conservative breast surgeries, as well as the early treatment of metastasis. Mechanisms of resistance to the drugs include the action of protein associated with the efflux of drugs from the intracellular environment hindering their activity; one of the most studied proteins is P-glycoprotein codified by the MDR-1 gene. The presence of polymorphisms can determine dif- ferent physiological actions of these proteins, intervening with the