My primary research efforts focus on how nutritional, hormonal, and genetic factors are related to various malignancies, especially those of the prostate and large bowel. Much of this work is based on the Nurses' Health Study, the Health Professionals Follow-Up Study and the Physicians’ Health Study cohorts. For prostate cancer, my work has centered on the role of specific antioxidants, particularly lycopene, and on the potentially deleterious effects of diets high in calcium and dietary fat. In addition to establishing risk factors, we have been interested in understanding etiologic mechanisms that will help provide a solid scientific rationale for preventive strategies. Specifically, I have studied how nutritional factors influence prostate cancer through modulating levels of insulin-like growth factors (IGFs) and binding proteins, insulin, vitamin D metabolites, and steroid hormones. More recently, our work has examined the role of obesity and energy balance in the progression of prostate cancer.