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Key words: apoptosis, breast cancer, early diagnosis, P2X^sub 7^ receptors
Summary
Determining the risk that a particular area of hyperplastic breast tissue will progress to cancer is difficult and is currently expressed only as a general risk factor within the population. Using an antibody against the apoptotic purinergic receptor P2X^sub 7^, we examined 40 cases each of the following histological categories: normal, moderate, florid and atypical hyperplasia, lobular carcinoma in situ, ductal carcinoma in situ, invasive lobular and invasive ductal carcinoma. These were previously diagnosed by H& E and supplied by clinical laboratories as tissue sections. Normal and mildly hyperplastic epithelium was devoid of the cytolytic P2X^sub 7^ receptors whereas all epithelial cells in all cases of in situ or invasive lobular or ductal carcinoma labelled intensely. The lobular and ductal in situ cases labelled intracellularly while the invasive epithelial cancer cells showed intense cell surface label indicating an attempt was being made to induce apoptosis. All these receptors however are non-functional and thus unable to induce apoptosis. Approximately 10% of all hyperplastic lobules examined in the biopsied tissue, regardless of H& E classification, labelled for P2X^sub 7^, which is suggestive of early metabolic cancerous change. The acini within lobules were either completely labelled with P2X^sub 7^ or were completely devoid of the receptor. A potential advantage of this method lies in identifying early cancerous change in hyperplastic lobules and in establishing the true extent of cancerous spread in infiltrating lesions, thus facilitating the task of reporting clear surgical margins.
Introduction
Histological and cytological features as demonstrated by haematoxylin and eosin (H& E) staining of tissue sections currently form the basis for the classification of breast cancer. Normal acini are composed of a layer of myoepithelial cells adjacent to the basement membrane that interact with the underlying stroma and an epithelial layer with secretory and absorptive functions on the ductal aspect [1].
Epithelial hyperplasia, sometimes called papillomatosis or epitheliosis, is a relatively common benign microscopic lesion in the breast in women over 30 years of age. The condition involves an increase in the number of layers of epithelial cells through increased proliferation or reduced apoptosis. These cells are heterogeneous and proliferate in layers that extend to ultimately fill the duct lumen. Mild epithelial hyperplasia...