A multicountry ecologic study of risk and risk reduction factors for prostate cancer mortality

Objective: The objective of this research is to identify and determine the relative importance of dietary and environmental risk and risk reduction factors for prostate cancer mortality. Materials and Methods: A multicountry ecologic approach was used in multivariate regression analyses with prostate cancer mortality rates and dietary factors and solar ultraviolet-B (UV-B) radiation. Prostate cancer mortality rates for 32 predominantly Caucasian countries for the late 1990s were obtained from the World Health Organization. Dietary supply data were obtained from the Food and Agriculture Organization. Annual solar UV-B dose data were obtained from European ground stations and used to estimate values elsewhere. Linear and multiple linear regression analyses were conducted for all 32 countries as well as the 20 European countries. Results: The strongest risk factor for prostate cancer mortality was animal products, with the nonfat portion of milk and alcohol being somewhat weaker; the strongest risk reduction factors were onions, other protective vegetable products (excluding alcohol, oils, and sweeteners), and solar UV-B radiation. Dietary data for 1979-81 yielded the highest correlations. Conclusions: These results are consistent with insulin-like growth factor-I (IGF-I), being an important risk factor for prostate cancer, with alcohol and calcium being less important risk factors, and with allium family vegetables, and, to a lesser extent, vitamin D being important risk reduction factors. These results should provide guidance for additional studies on dietary and environmental links to prostate cancer. (C) 2003 Elsevier B.V. All rights reserved.