Background
Mucinous cystic tumors of the pancreas include histologically benign but premalignant mucinous cystic neoplasms and mucinous cystadenocarcinoma. The molecular events leading to transformation from a benign to a malignant mucinous tumor are not known. Overexpression of EGF-R and detection of an estrogen-induced protein (pS2) has been demonstrated in ductal adenocarcinomas of the pancreas, but these factors have not been evaluated in mucinous cystic tumors.

Design
Twenty-six mucinous tumors were examined for EGF-R, pS2 protein, and estrogen and progesterone receptors.

Results
Eight (61.2%) of 13 malignant tumors exhibited increased expression of EGF-R, whereas 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 benign tumors (P=.480). Estrogen and progesterone receptors were not detected in the epithelium of either tumor type. The median survival time of the patients with EGF-R-negative tumors was 29.0 months compared with 14.5 months for those with EGF-R-postive tumors, but this difference did not reach significance owing to the small population size.

Conclusions
Overexpression of EGF-R in mucinous cystic tumors, as in ductal adenocarcinomas, may be an important feature associated with malignancy 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 expression of pS2 protein appears to be independent of estrogen and may play a role in the proliferative activity of mucinous tumors. However, pS2 expression is not a feature associated exclusively with malignancy.

(Arch Surg. 1995;130:69-72)