Prostate cancer: another aspect of the insulin-resistance syndrome?

Insulin resistance and compensatory hyperinsulinaemia are thought to be the underlying factors in the metabolic or insulin-resistance syndrome and can be controlled by diet and exercise. Hyperinsulinaemia has been shown to have a direct effect on the live, suppressing the production of sex hormone-binding globulin (SHBG) and insulin-like growth factor-binding proteins 1 and 2 (IGFBP-1, -2) while stimulating the production of insulin-like growth factor 1 (IGF-1). These factors have been proposed to be important modulators of hormone-related cancers, such as prostate cancer. Men adopting a low-fat diet and daily exercise reduced their levels of serum insulin and IGF-1, while increasing their levels of IGFBP-1 and sex hormone-binding globulin (SHBG). Cell-culture studies with LNCaP prostate cancer cells showed apoptosis of tumour cells and a reduction in serum-stimulated cell growth in the post diet and exercise serum. These results suggest that prostate cancer may be another aspect of the insulin-resistance syndrome and that adopting a low-fat diet combined with regular exercise may reduce the risk for prostate and other hormone-related cancers. This needs to be tested with prospective studies.