EXPRESSION OF OPIOID-PEPTIDES IN CELLS AND STROMA OF HUMAN BREAST-CANCER AND ADENOFIBROMAS

The expression of beta-endorphin, Met-enkephalin and Leu-enkephalin was studied in 63 malignant and benign human breast tumors using immunohistochemical methods. Among invasive ductal carcinomas, 93% were positive for beta-endorphin, 87% for Leu-enkephalin and 90% for Met-enkephalin, in both the tumor stroma and the cell bodies. Enkephalin was predominant in cells, whereas endorphin was predominant in stroma. Nearly the same distribution was found in adenofibromas. In pericancerous normal tissue, neuropeptides were predominantly expressed in the stroma. Although the neuropeptide expression is not cancer-specific, it could be cancer-related, since the results suggest that the neuropeptide expression could reflect the host response to cancer cells and not only the cancer cell activity. The possibility of a direct action of the nervous system on stroma reaction and then on cancer cells is discussed.