A new test that can predict a man's risk of prostate cancer may be on the horizon. The test measures insulin-like growth factor-1 (IGF-1), a growth factor known to stimulate growth and inhibit death in normal and cancerous prostate cells. The net effect of this growth factor is to increase the likelihood of mutations in prostate cells, then to protect the mutated cells from programmed cell death, the body's natural mechanism for ridding itself of dysfunctional cells.

The data revealed a significantly increased risk of prostate cancer in men with the highest levels of IGF-1, compared with those with the lowest levels. According to the report, men with the highest levels had a 4.3-fold increased risk of prostate cancer compared with those who had the lowest IGF-1 levels. Though the findings have no immediate clinical implications, the researchers hope their report will "spur additional research" on the predictive value of IGF-1 in prostate cancer. According to a commentary in Science, scientists have already found an equally strong association between IGF-1 levels and the risk of breast cancer, and they are now seeking links to colon cancer.

If the link between IGF-1 and prostate cancer is confirmed, IGF levels could be used to help identify men who are at risk before they develop cancer. By contrast, PSA levels are most useful in predicting disease progression in men already diagnosed with prostate cancer or its precursors. In addition, the findings may lead to new research into dietary or pharmaceutical interventions that can reduce IGF-1 levels, and potentially prevent the development of prostate cancer.

Science (1998;279:475, 563-566)