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Cancer Causes Control. 2000 Aug;11(7):617-26.

Effects of beta-carotene supplementation on cancer incidence by baseline characteristics in the Physicians' Health Study (United States).

Author information

  • 1Department of Medicine, Brigham and Women's Hospital, Boston, MA 02215, USA. ncook@rics.bwh.harvard.edu

Abstract

OBJECTIVES:

The Physicians' Health Study (PHS) was a randomized trial of beta-carotene (50 mg, alternate days) and aspirin in primary prevention of cancer and cardiovascular disease among 22,071 US male physicians. This report updates results for beta-carotene and examines effect modification by baseline characteristics.

METHODS:

Beta-carotene's effect on cancer over nearly 13 years was examined overall and within subgroups defined by baseline characteristics using proportional-hazards models.

RESULTS:

2667 incident cancers were confirmed, with 1117 prostate, 267 colon, and 178 lung cancers. There were no significant differences with supplementation in total (relative risk (RR) = 1.0, 95% confidence interval (CI) = 0.9-1.0); prostate (RR = 1.0, 95% CI = 0.9-1.1); colon (RR = 0.9, 95% CI = 0.7-1.2); or lung (RR = 0.9, 95% CI = 0.7-1.2) cancer, and no differences over time. In subgroup analyses, total cancer was modestly reduced with supplementation among those aged 70+ years (RR = 0.8, 95% CI = 0.7-1.0), daily drinkers of alcohol (RR = 0.9, 95% CI = 0.8-1.0), and those in the highest BMI quartile (RR = 0.9, 95% CI = 0.7-1.0). Prostate cancer was reduced with supplementation among those in the highest BMI quartile (RR = 0.8, 95% CI = 0.6-1.0), and colon cancer was reduced among daily drinkers of alcohol (RR = 0.5, 95% CI = 0.3-0.8).

CONCLUSIONS:

The PHS found no overall effect of beta-carotene on total cancer, or the three most common site-specific cancers. The possibility of risk reduction within specific subgroups remains.

PMID:
10977106
[PubMed - indexed for MEDLINE]
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