RESUMO
Objective: The aim of this work was to evaluate the immunohistochemical expression of P-glycoprotein and its correlation tothe response to chemotherapy with antraciclin in women affected by stage III breast carcinoma. Methods: In this transversalstudy, 88 prontuaries of patients affected by local ductal infiltrative advanced carcinoma who had received neo-adjuvantchemotherapy with antraciclin, excepting the inflammatory ones, had been analyzed from June 1996 to November 2003, in theClinic of Clinical Oncology of CAISM/UNICAMP. Tumors was biopsed before the treatment (core or incisional biopsy or) andsubmitted to immunohistochemical examination, system envision peroxidase, using C494 (Signet) and C219 (Signet) anti-Pglycoproteinmonoclonal antibodies. Cytoplasmic or transmembrane coloration in at least 10% was considered positive. Thepositive external control used was of human kidney normal tissue. Clinical response was evaluated before and surgery, andafter at least two chemotherapy cycles and data were correlated with P-glycoprotein expression. Fisher accurate test or quisquarewas used to evaluate the possible associations. Results: P-glycoprotein positivity in the sample was 23.86%. Theobjective clinical response to chemotherapy was similar in cases with and without P-glycoprotein expression, considering theprimary tumor (57.1% versus 58.2%), the armpits (67.7% versus 78.7%) and total response (57.1% versus 65,7 %, p =0,604). Conclusion: The relation between P-glycoprotein expression and the clinical response to neo-adjuvant chemotherapywas not found, suggesting that this marker is not to be considered a predictive factor of response to chemotherapy withantraciclin.