Cyclooxygenase-2 and human epidermal growth factor receptor type 2 (HER-2) expression simultaneously in invasive and in situ breast ductal carcinoma

context and objective: cyclooxygenase-2 (cox-2) and human epidermal growth factor receptor type 2 (her-2) are associated with tumorigenesis. studies have shown that her-2 can regulate cox-2 expression. the aim of this study was to evaluate the correlation between cox-2 and her-2 expression in normal breast epithelium and in ductal carcinoma in situ (dcis) and invasive ductal carcinoma (idc) present in the same breast. design and setting: cross-sectional study at the mastology unit of the department of gynecology and obstetrics, santa casa de misericórdia de s？o paulo hospital. methods: cox-2 and her-2 were detected using immunohistochemistry on 100 tissue fragments. her-2 > +2 was subjected to fluorescence in situ hybridization (fish). results: cox-2 expression was detected in 87%, 85% and 75% of idc, dcis and normal epithelium, respectively. her-2 expression was detected in 34% of idc and 34% of dcis. cox-2 in dcis correlated with her-2 in idc (p = 0.049) and dcis (p = 0.049). cox-2 in normal epithelium correlated with her-2 in idc (p = 0.046) and dcis (p = 0.046). cox-2 in idc was not associated with her-2 (p = 0.235). comparison between cox-2 and her-2 in dcis showed that there was a statistically significant difference with regard to nuclear grades ii and iii and presence of comedonecrosis (p < 0.001). in idc, there was significant expression with nuclear grades ii and iii and histological grade ii (p < 0.001). conclusions: our findings provide evidence that her-2 and cox-2 regulate each other