BOSTON, MASSACHUSETTS. An international team of researchers from the Harvard Medical School, the University of Athens, and the Karolinska Institute in Sweden report that high levels of insulin-like growth factor 1 (IGF-1) in the blood are associated with an increased risk of prostate cancer. Their study involved 52 men with confirmed prostate cancer, 52 men with benign prostatic hyperplasia (BPH - enlarged prostate gland) and 52 healthy controls. Analysis of blood samples from the study participants showed that increased levels of IGF-1 corresponded to higher risks of prostate cancer. An increment of 60 nanograms of IGF-1 per milliliter of blood corresponded to an almost two-fold increase in the risk of prostate cancer. No relationship was found between IGF-1 levels and the risk of having an enlarged prostate. High levels of circulating testosterone were also associated with a higher risk of prostate cancer while higher levels of dehydroepiandrosterone sulphate (DHEAS) were associated with increased incidence of BPH. Although the researchers do not rule out that prostate cancer in itself could increase IGF-1 levels they nevertheless conclude that high IGF-1 levels may promote prostate cancer, but do not increase the risk of BPH. They also point out that previous research found a significant correlation between high IGF-1 levels and the incidence of breast cancer in women. NOTE: This study was partially funded by Monsanto, the manufacturer of bovine growth hormone (BST, Posilac). Milk from BST-treated cows has been found to contain much higher levels of IGF-1 than does normal milk.
Mantzoros, C.S., et al. Insulin-like growth factor 1 in relation to prostate cancer and benign prostatic hyperplasia. British Journal of Cancer, Vol. 76, No. 9, 1997, pp. 1115-18