Fat and meat intake and prostate cancer risk: The multiethnic cohort study

Abstract

Dietary fat and meat as potential risk factors for prostate cancer have been the focus of many epidemiologic investigations, and findings from recent studies in particular have been inconsistent. Therefore, we examined the association between these exposures and prostate cancer risk in the Multiethnic Cohort Study. The analyses included 82,483 men in Hawaii and Los Angeles aged 45, who completed a detailed quantitative food frequency questionnaire in [1993][1994][1995][1996]. During the follow-up period of 8 years, a total of 4,404 incident cases, including 1,278 nonlocalized or highgrade cancer cases, were identified. Cox proportional hazard models were used to estimate relative risks of prostate cancer after adjustment for time on study, ethnicity, family history of prostate cancer, education, body mass index, smoking status and energy intake. Intake of different types of fat (total, saturated, monounsaturated or polyunsaturated), n-6 fatty acid, cholesterol, various meats, and fats from meat showed no association with overall prostate cancer risk or with nonlocalized or high-grade prostate cancer. Furthermore, we found little evidence of any relation of fat and meat intake with prostate cancer risk within any of the 4 racial/ethnic groups (African Americans, Japanese Americans, Latinos and Whites). There was a suggestion of a protective effect of n-3 fatty acid intake that was limited to Latinos and Whites. However, overall, our findings from a large cohort study of ethnically diverse population give no indication that intake of fat and meat substantially affects prostate cancer risk. ' 2007 Wiley-Liss, Inc.Key words: prostate cancer; fat; meat; cohort study; multiethnic population In the last 3 decades, epidemiologic studies on prostate cancer have extensively investigated dietary risk factors. 1,2 More than any other dietary components, fat and meat have been the focus of these studies. Although findings from early studies were generally supportive of a positive association, findings from recent studies have been much less consistent. 3,4 Indeed, the biologic role of fat in prostate cancer incidence and progression still remains unclear. Meat consumption may be related to prostate cancer risk through its content of several potential carcinogens in addition to its fat content. 2,3 In studies of prostate cancer, fat has been classified in several ways, including total, saturated, monounsaturated, polyunsaturated fat and animal product fat; n-3 and n-6 polyunsaturated fat; and more recently, individual fatty acids. 2 Most studies showed either no association 5-11 or a positive association 12-16 of total, saturated or animal fat with risk, though some studies suggested that consumption of fatty fish containing abundant long-chain polyunsaturated fatty acids may be protective. [17][18][19][20] Experimental studies have suggested that specific fatty acids promote or suppress prostate tumor development, but epidemiologic investigations on individual fatty acids have yielded inconsistent findings. 7,[21][22][23][2...

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