There is compelling evidence that growth factors are involved in mediating estrogen action in target tissues. The role of growth factors in the development and progression of endometrial cancer is less clear. Steroid hormones can regulate the expression of the transforming growth factors and epidermal growth factor receptors in endometrial cancer cells in culture. It is also possible to demonstrate that these growth factors function in an autocrine fashion to regulate proliferation of endometrial cancer cells in culture. Constitutive expression or overexpression of such autocrine/paracrine factors and/or their receptors may be important in the growth progression of endometrial neoplasia. However, to date the evidence to support the hypothesis is limited.