Is IGF-1 likely to increase the risk of specific kinds of cancer?
A. It is highly likely that IGF-1 promotes transformation of normal breast cells to breast cancers. In addition, IGF-1 maintains the malignancy of human breast cancer cells, including their invasiveness and ability to spread to distant organs. (Increased levels of IGF-1 have similarly been associated with colon and prostate cancers.) The prenatal and infant breast is particularly susceptible to hormonal influences. Such imprinting by IGF-1 may increase future breast cancer risks, and may also increase the sensitivity of the breast to subsequent unrelated risks such as mammography and the carcinogenic and estrogen-like effects of pesticide residues in food, particularly in pre-menopausal women. Q. Are cows adversely affected by elevated IGF-1 levels? A. Cows injected with rBGH show heavy localization of IGF-1 in breast (udder) epithelial cells. This does not occur in untreated cows. Cows are also affected in other ways by rBGH, through increased rates of mastitis, an udder infection. In
