RELATION OF EPIDERMAL GROWTH-FACTOR RECEPTOR AND ESTROGEN RECEPTOR-INDEPENDENT PS2 PROTEIN TO THE MALIGNANT TRANSFORMATION OF MUCINOUS CYSTIC NEOPLASMS OF THE PANCREAS

Objective: To evaluate the role of epidermal growth factor receptor (E GF-R) and pS2 protein in the evolution of malignancy in mucinous cysti c tumors of the pancreas. Background: Mucinous cystic tumors of the pa ncreas include histologically benign but premalignant mucinous cystic neoplasms and mucinous cystadenocarcinoma. The molecular events leadin g to transformation from a benign to a malignant mucinous tumor are no t known. Overexpression of EGF-R and detection of an estrogen-induced protein (pS2) has been demonstrated in ductal adenocarcinomas of the p ancreas, but these factors have not been evaluated in mucinous cystic tumors. Design: Twenty-six mucinous tumors were examined for EGF-R, pS 2 protein, and estrogen and progesterone receptors. Results: Eight (61 .2%) of 13 malignant tumors exhibited increased expression of EGF-R, w hereas EGF-R was not detected in any of the 13 benign tumors (P=.002). The pS2 protein was detected in nine of 11 malignant and 11 of 11 ben ign tumors (P=.480). Estrogen and progesterone receptors were not dete cted in the epithelium of either tumor type. The median survival time of the patients with EGF-R-negative tumors was 29.0 months compared wi th 14.5 months for those with EGF-R-positive tumors, but this differen ce did not reach significance owing to the small population size. Conc lusions: Overexpression of EGF-R in mucinous cystic tumors, as in duct al adenocarcinomas, may be an important feature associated with malign ancy and may have prognostic significance. Failure to detect EGF-R in histologically benign epithelium suggests that the upregulation of EGF -R may be important in the evolution of aggressive behavior. The expre ssion of pS2 protein appears to be independent of estrogen and may pla y a role in the proliferative activity of mucinous tumors. However, pS 2 expression is not a feature associated exclusively with malignancy.