Steroid receptor variants and their potential role in cancer.

Variant forms of steroid receptors that possess altered structure have been described in a number of human cancers. This is particularly true for tumors of the breast, which frequently contain a variety of defective estrogen receptors. Evidence for the existence of steroid receptor variants in human tumors is summarized along with what is known regarding the functional behavior of these aberrant receptors. This article also discusses the implications that steroid receptor variants have for the diagnosis and treatment of tumors of the breast and other human malignancies.