Gene alterations and overexpression of various oncogenes and cell-cycle regulators are important in tumor development. In a population based series of 316 endometrial carcinomas with long and complete follow-up we investigated the distribution of HER-2/neu and EGFR expression and copy number alteration in endometrial cancers. HER-2/ neu, EGFR and Ki-67 expression in curettage and hysterectomy specimens were studied immunohistochemically for expression in relation to molecular markers and clinical phenotype. Fresh tumor samples (n=76) were studied by global characterization of genetic alterations by single nucleotide polymorphism (SNP) array for detection of high level amplification for HER-2/neu and EGFR. Pathological expression of HER-2/neu in curettage was detected in 23% which significantly correlated to high FIGO stage, non-endometrioid subtype, high grade and aneuploidy. In hysterectomy specimens, pathological HER-2/neu staining was seen in 13% which correlated significantly with high FIGO stage, non-endometrioid subtype, high proliferation and poor survival (p=0.009). Expression of EGFR was examined with three different antibodies, but none showed significant correlation with molecular markers or clinical phenotype. High level amplification of HER-2/neu or EGFR was seen in only one out of 76 samples, respectively. High proliferation estimated in tumors from hysterectomy specimens showed independent prognostic impact and was superior to estimation in curettage specimens as a prognostic marker. In conclusion, high level amplification of HER-2/neu or EGFR is infrequent in endometrial cancer. Pathological HER-2/neu staining identifies endometrial carcinomas with an aggressive phenotype, high proliferation and patients with poor survival in a population based setting. These results motivate further clinical trials with trastuzumab based on HER-2/neu status in endometrial carcinomas.

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