Risk factors for prostate cancer.

The risk for prostate cancer increases with age, with a family history of the disease and with living in a Westernized society, especially for blacks. Although there is no doubt that genetic factors are important, and might explain some of the geographical variation in rates, the differences between populations are so large that environmental factors must also be important. The evidence suggesting that dietary fat and/or meat may increase risk is quite consistent. The observed relative risks are small (about a 30% increase for high v. low consumption) but may have been underestimated because of inaccurate measurement of diet and further study of this topic is needed. The evidence does not support the hypothesis that carotene intake is associated with risk. There is reasonably consistent evidence suggesting that an increased risk for prostate cancer is associated with a high level of sexual activity and/or a history of sexually transmitted disease, and with vasectomy. These observations need further investigation to eliminate the possibility that they are due to biases. Much more information is needed. Prospective studies, with dietary and lifestyle questionnaires and stored blood samples, are needed to answer the outstanding questions.