Estrogen receptor gene amplification occurs rarely in ovarian cancer

Abstract

Amplification of the gene encoding estrogen receptor-α occurs in about 20% of breast cancers and is an important mechanism for estrogen receptor overexpression in this tumor type. In ovarian cancer, overexpression of estrogen receptor protein has been described in more than two thirds of cases. To study a potential role of estrogen receptor-α gene amplification for estrogen receptor overexpression in ovarian cancer, a tumor tissue microarray containing 428 ovarian cancers was analyzed by fluorescence in situ hybridization for estrogen receptor-α gene amplification and immunohistochemistry for estrogen receptor expression. The estrogen receptor-α gene status was successfully determined in 243 of 428 arrayed cancers. Estrogen receptor gene amplification was found in 5 of 243 (2%) of tumors. Amplification levels were usually low, with 4-8 estrogen receptor-α gene copies. However, one case had a high-level amplification, with more than 30 estrogen receptor-α gene copies. All five amplified tumors were estrogen receptor positive, with 3 of 5 tumors showing highest (Allred score, 7-8) estrogen receptor levels. The data demonstrate that estrogen receptor-α amplification occurs only rarely in ovarian cancer. © 2009 USCAP, Inc All rights reserved.