Beta-carotene supplementation for patients with low baseline levels and decreased risks of total and prostate carcinoma.

Abstract

BACKGROUND:

The Physicians' Health Study was a randomized, double-blind, placebo-controlled trial using a 2x2 factorial design including supplementation with beta-carotene (50 mg every other day) in the primary prevention of cancer among 22,071 U.S. male physicians ages 40-84 years at randomization. Before randomization, the authors collected baseline blood specimens to determine whether any benefit was greater among or confined to those with low baseline levels of beta-carotene.

METHODS:

Baseline blood samples were collected from 14,916 participants. These samples were assayed, according to a nested case-control design, from 1439 men subsequently diagnosed with cancer over 12 years of follow-up (631 with prostate carcinoma) and 2204 controls matched by age and smoking habits.

RESULTS:

Men in the lowest quartile for plasma beta-carotene at baseline had a marginally significant (P = 0.07) increased risk of cancer compared with those in the highest quartile (relative risk [RR] = 1.30, 95% confidence interval [CI], 0.98-1.74). Men in the lowest quartile assigned at random to beta-carotene supplementation had a possible but nonsignificant decrease in overall cancer risk (RR = 0.83, 95% CI, 0.63-1.09) compared with those assigned to placebo. This was primarily due to a significant reduction in the risk of prostate carcinoma (RR = 0.68, 95% CI, 0. 46-0.99) in this group. After the first 2 years of follow-up were excluded, the results were virtually unchanged.

CONCLUSIONS:

These prespecified subgroup analyses appeared to support the idea that beta-carotene supplementation may reduce risk of prostate carcinoma among those with low baseline levels. Further follow-up of this population will help determine whether these findings are valid.

• Authors: N R Cook, M J Stampfer, J Ma, J E Manson, F M Sacks, J E Buring, C H Hennekens
• Journal: Cancer (Cancer) Vol. 86 Issue 9 Pg. 1783-92 (Nov 01 1999) ISSN: 0008-543X [Print] United States
• PMID: 10547552 (Publication Type: Clinical Trial, Journal Article, Randomized Controlled Trial, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• beta Carotene

Topics

• Adult
• Aged
• Aged, 80 and over
• Case-Control Studies
• Colonic Neoplasms (blood, prevention & control)
• Dietary Supplements
• Double-Blind Method
• Epidemiologic Studies
• Follow-Up Studies
• Humans
• Lung Neoplasms (blood, prevention & control)
• Lymphoma (blood, prevention & control)
• Male
• Melanoma (blood, prevention & control)
• Middle Aged
• Prostatic Neoplasms (blood, prevention & control)
• Risk
• Smoking
• beta Carotene (blood, therapeutic use)