Stimulatory and inhibitory growth factors and breast cancer

While steroid hormones act as endocrine effectors of growth and development of normal breast and of carcinogenesis and progression of malignant breast, recent evidence suggests that local hormonal effectors also exist. These are the growth regulatory growth factors. This article summarizes current status of our understanding of structure and function of growth factors secreted by the normal and malignant mammary epithelium. While growth inhibitory factors and their receptors generally suppress development of the transformed phenotype and promote differentiation, growth stimulatory factors and their receptors may be necessary for both normal proliferation and early stages of malignant progression of breast cancer. Overexpression of two receptors, c-erbB-2 and EGF receptor, have also been associated with poor prognosis in the clinical disease.