Sequential phenotype changes in progressive lesions of breast carcinoma

Malignant transformation is the result of genetic events, translated into sequential acquisitions of multiple abnormalities in the control of cellular growth and cell cycle regulation. We determined the expression of the estrogen receptor (ER), progesterone receptor (PR), c-erbB-2 and p53 gene products in a patient with mixed (ductal and lobular) invasive breast carcinoma bearing different coexisting lesions. The purpose of the study was to establish a possible correlation between the expression pattern for these molecules and the histological appearance of the breast tumor. Our results showed no positivity for ER. PR expression was restricted to normal epithelium, simple hyperplasia and in situ carcinoma. c-erbB-2 was detected in all lesions with the exception of normal epithelium and immunostaining for p53 was found positive only in in situ and invasive carcinoma. These findings support the hypothesis of tumorigenesis as a multistep process and as a sum of changes, each representing an advantageous acquisition for the malignant cells' behavior. The loss of hormone receptors' expression occurred as an early event in this case, while the p53 mutations were found only in more advanced neoplastic lesions.