Split Prostate Cancer Four Ways, Willett Says

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Researchers recognize that aggressive and slow-growing prostate cancers are probably different entities, and data suggest that the risk factors for developing the two types differ as well. Now, Walter Willett , M.D., Dr.P.H., and colleagues are proposing that the causes of prostate cancer in younger men differ from the causes of the disease in older men. If their hypothesis is correct, then researchers will have to divide prostate cancer cases four ways—aggressive versus nonaggressive and younger versus older age of onset—to identify risk factors associated with the disease.

Historical data and results from the ongoing Health Professionals Follow-Up Study already suggest that the cause of the disease differs between these younger and older men, said Willett, chairman of the department of nutrition and professor of medicine at Harvard School of Public Health in Boston. For example, several studies have suggested that high dairy consumption or calcium intake increases the risk of aggressive disease, but it has no effect on the risk of organ-confined disease. Moreover, researchers have found that a high body mass index protects against prostate cancer during a man's early years, producing as much as a 50% reduction in risk of disease when a man's body mass index at age 21 is considered, but it is associated with a modest increase in risk of disease in men more than age 60.