The specific mechanisms that lead to the development of prostate cancer are still unknown, but several risk factors for the disease have been identified. Incidence increases with age—prostate cancer seldom develops before the age of 40 and is chiefly a disease found in men over the age of 65. It is most common in North America and in northwestern Europe but rare in South America, the Near East, and Africa.
In the United States, black males, who suffer from the disease 37 percent more often than white males, have the world’s highest incidence. A growing body of evidence links diets rich in animal fats with prostate cancer. Dietary differences are believed to explain why the incidence of prostate cancer is 120 times greater in the United States than in China, where fatty foods are not part of the general diet. Some foods seem to act as a shield against this disease. Studies show that tomato-based products protect against prostate cancer, possibly because tomatoes are rich in a substance called lycopene. Lycopene is an antioxidant, a chemical agent that inhibits or retards the cellular process of oxidation. Too much cellular oxidation can be dangerous to a person’s health because it produces molecules called free radicals that increase the risk of cancer developing in body tissues. Long-term, moderate doses of vitamin E, another type of antioxidant, may block the progress of prostate tumors. Environmental factors, such as workplace exposures to cadmium, have also been associated with increased risk of prostate cancer. Family history plays another important role. Men whose fathers or brothers develop prostate cancer are more likely to develop the disease. Researchers are beginning to identify genetic markers of prostate cancer. For instance, the gene known as hereditary prostate cancer 1 (HPC1) appears to significantly predispose men to prostate cancer when inherited in a mutated form.