Background: Tumors of borderline malignancy are still a controversial subgroup of ovarian neoplasms. The expression of several cell regulatory proteins was studied to characterize the molecular phenotype of these tumors, and to compare them with their benign and malignant counterparts.
Methods: Specimens from 22 patients with tumors of borderline malignancy (11 serous and 11 mucinous tumors), 12 patients with benign tumors, and 16 patients with invasive ovarian carcinomas were evaluated for expression of epidermal growth factor receptor (EGFR), HER-2/neu, PTP1B, and p53 by immunohistochemical techniques.
Results: One or both of the tyrosine kinase growth factor receptors EGFR and HER-2/neu was expressed by 42% of benign, 59% of borderline, and 81% of malignant ovarian tumors. EGFR was expressed in a significantly greater fraction of malignant lesions (69%) than borderline lesions (18%) (P< 0.004). EGFR expression was not observed among the 11 mucinous borderline tumors. HER-2/neu was expressed by 50% of borderline tumors and was not a marker for malignancy. The tyrosine phosphatase PTP1B was expressed by a similar fraction of benign (17%), borderline (27%), and malignant (19%) tumors. The number of cases studied precluded correlation of kinase and phosphatase activity. However, among 12 tumors with PTP1B expression, 9 also expressed EGFR or HER-2/neu. Overexpression of p53 was observed only in malignant serous tumors and was not found in malignant mucinous, borderline, or benign lesions.
Conclusions: Either EGFR or HER-2/neu was detected in a majority of borderline cancers. PTP1B was present only in a minority of these cancers. Frankly malignant serous lesions differed from borderline and benign tumors with regard to expression of EGFR and overexpression of p53.