Effects of Supplemental α-Tocopherol and β-Carotene on Colorectal Cancer: Results from a Controlled Trial (Finland)

• Published in: Cancer causes & control 2000-03, Vol.11 (3), p.197-205
• Main Authors: Albanes, Demetrius, Malila, Nea, Taylor, Philip R., Huttunen, Jussi K., Virtamo, Jarmo, Edwards, Brenda K., Rautalahti, Matti, Hartman, Anne M., Barrett, Michael J., Pietinen, Pirjo, Hartman, Terryl J., Sipponen, Pentti, Lewin, Klaus, Teerenhovi, Lasse, Hietanen, Paivi, Tangrea, Joseph A., Virtanen, Mikko, Heinonen, Olli P.
• Format: Article
• Language: English
• Subjects: Adenoma; Aged; Arm; beta Carotene - administration & dosage; Body mass index; Cancer; Colorectal cancer; Colorectal Neoplasms - epidemiology; Colorectal Neoplasms - mortality; Colorectal Neoplasms - prevention & control; Dietary Supplements; Double-Blind Method; Experimentation; Finland - epidemiology; Humans; Incidence; Male; Middle Aged; Mortality; P values; Placebos; Research Papers; Risk Factors; Smoking; Vitamin E; Vitamin E - administration & dosage
• ISSN: 0957-5243; 1573-7225
• DOI: 10.1023/A:1008936214087

Background: Some epidemiological investigations suggest that higher intake or biochemical status of vitamin E and β-carotene might be associated with reduced risk of colorectal cancer. Methods: We tested the effects of α-tocopherol and β-carotene supplementation on the incidence of colorectal cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, a double-blind, placebo-controlled trial among 29,133 50-69-year-old male cigarette smokers. Participants were randomly assigned to receive α-tocopherol (50 mg), β-carotene (20 mg), both agents, or a placebo daily for 5-8 years. Incident colorectal cancers (n = 135) were identified through the nationwide cancer registry, and 99% were histologically confirmed. Intervention effects were evaluated using survival analysis and proportional hazards models. Results: Colorectal cancer incidence was somewhat lower in the α-tocopherol arm compared to the no α-tocopherol arm, but this finding was not statistically significant (relative risk (RR) = 0.78, 95% confidence interval (CI) 0.55-1.09; log-rank test p = 0.15). β-Carotene had no effect on colorectal cancer incidence (RR = 1.05, 95% CI 0.75-1.47; log-rank test p = 0.78). There was no interaction between the two substances. Conclusion: Our study found no evidence of a beneficial or harmful effect for β-carotene in colorectal cancer in older male smokers, but does provide suggestive evidence that vitamin E supplementation may have had a modest preventive effect. The latter finding is in accord with previous research linking higher vitamin E status to reduced colorectal cancer risk.