American Journal of Epidemiology Advance Access published online on October 12, 2007
American Journal of Epidemiology, doi:10.1093/aje/kwm268
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Original Contribution |
Calcium, Dairy Foods, and Risk of Incident and Fatal Prostate Cancer
The NIH-AARP Diet and Health Study
1 Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD
2 Division of Cancer Prevention, National Cancer Institute, Bethesda, MD
3 AARP, Washington, DC
Correspondence to Dr. Yikyung Park, Division of Cancer Epidemiology and Genetics, 6120 Executive Boulevard, Bethesda, MD 20852 (e-mail: parkyik{at}mail.nih.gov).
Received for publication March 21, 2007. Accepted for publication May 23, 2007.
Calcium and dairy foods in relation to prostate cancer were examined in the National Institutes of Health (NIH)-AARP (formerly known as the American Association of Retired Persons) Diet and Health Study (1995/1996–2001). Diet was assessed with a food frequency questionnaire at baseline. Multivariate relative risks and 95% confidence intervals were estimated by Cox regression. During up to 6 years of follow-up (n = 293,888), the authors identified 10,180 total prostate cancer cases (8,754 nonadvanced, 1,426 advanced, and 178 fatal cases). Total and supplemental calcium were unrelated to total and nonadvanced prostate cancer. However, a statistically nonsignificant positive association with total calcium was observed for advanced (
2,000 vs. 500–<750 mg/day: relative risk (RR) = 1.25, 95% confidence interval (CI): 0.91, 1.71; ptrend = 0.06) and fatal (
1,000 vs. 500–<750 mg/day: RR = 1.39, 95% CI: 0.92, 2.09; ptrend = 0.10) prostate cancer. Skim milk, but not other dairy foods, was associated with increased risk of advanced prostate cancer (
2 vs. zero servings/day: RR = 1.23, 95% CI: 0.99, 1.54; ptrend = 0.01). In contrast, calcium from nondairy foods was associated with lower risk of nonadvanced prostate cancer (
600 vs. <250 mg/day: RR = 0.82, 95% CI: 0.68, 0.99; ptrend = 0.04). Although the authors cannot definitively rule out a weak association for aggressive prostate cancer, their findings do not provide strong support for the hypothesis that calcium and dairy foods increase prostate cancer risk.
calcium; dairy products; prostatic neoplasms
Abbreviations: AARP, formerly known as the American Association of Retired Persons; CI, confidence interval; NIH, National Institutes of Health; RR, relative risk