The role of growth hormone in metastasis and angiogenesis of breast cancer.

Breast cancer is a complex disease which has many factors affecting its progression and metastasis. Although steroid hormones, especially oestrogen, are most commonly associated with breast cancer, growth hormone (GH) also plays a substantial role in its development and spread via the activation of downstream signalling pathways and the regulation of growth factors such as insulin-like growth factor-1 (IGF-1) and the vascular endothelial growth factor (VEGF). Breast cancer patients usually have elevated levels of GH and IGF-1 in their circulation. Growth hormone receptor (GHR) signalling enhances migratory ability of tumour cells and excess IGF-1 production promotes angiogenesis. Gaining a full understanding of the mechanisms behind GH and breast cancer will allow researchers to develop more therapeutics to treat this devastating disease.