Immunohistochemical evaluation of the HER-2 protein in the infiltrative lobular breast cancer.
AIM OF THE STUDY To investigate the correlation between the expression of HER-2 membrane protein and basic pathohistological parameters in cases of infiltrative breast cancer. MATERIAL AND METHODS Sixty-nine cases of lobular infiltrative breast cancer were investigated. Mastectomy with a dissection of axillary's lymph nodes was performed in all cases. Upon standard procedure of formalin fixation, embedding in paraffin and examination of slides stained with hematoxillin-eosin, a semiquantitaive method of evaluation of immunohistochemical expression of the HER-2 protein has been performed in all tissue samples of the tumor. RESULTS Majority of patients (91,3 %) were above 41 year-of-age. In the majority of cases (44,9 %) cancer's diameter ranged from 20-50 mm (pT2), with a moderate degree of differentiation (46,4 %), no signs of vascular invasion (50,7 %) and no metastases in axillary's lymph nodes (65,2 %). Evaluation of immunohistochemical expression of the HER-2 protein revealed that only the degree of tumor differentiation has been in statistically significant (p=0, 037) correlation with the intensity of the HER-2 protein expression. CONCLUSION In cases of lobular infiltrative breast cancer, oncogenic effect of the HER-2 protein was associated with the degree of cellular differentiation, while it was not in correlation with other pathological parameters of poorer prognosis, such as the size of tumor, presence of vascular invasion and occurrence of metastases in regional lymph nodes.