Effects of α-Tocopherol and β-Carotene Supplementation on Cancer Incidence and Mortality: 18-Year Post-Intervention Follow-Up of the Alpha-Tocopherol Beta-Carotene Cancer Prevention (ATBC) Study

摘要

In the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study among 29,133 Finnish male smokers aged 50–69 years, daily α-tocopherol (50 mg) for a median of 6.1 years decreased the risk of prostate cancer, whereas β-carotene (20 mg) increased risk of lung cancer and overall mortality. To determine the post-intervention effects of α-tocopherol and β-carotene, 25,563 men were followed 18 years for cancer incidence and all causes of mortality through national registers. Neither supplement had significant effects on post-trial cancer incidence. Relative risk (RR) for lung cancer (n=2,881) was 1.04 (95% confidence interval [CI], 0.96–1.11) among β-carotene recipients compared with nonrecipients. For prostate cancer (n=2,321) RR was 0.97 (95% CI, 0.89–1.05) among α-tocopherol recipients compared with nonrecipients with the preventive effect of α-tocopherol continuing approximately 8 years post-intervention. Body mass index significantly modified the effect of α-tocopherol on prostate cancer (P for interaction=0.01): RR 1.00 (95% CI, 0.88–1.14) in normal-weight men, 0.87 (95% CI, 0.77–0.98) in overweight men, and 1.25 (95% CI, 1.01–1.55) in obese men. The post-trial relative mortality (based on 16,686 deaths) was 1.02 (95% CI, 0.98–1.05) for α-tocopherol recipients compared with nonrecipients and 1.02 (95% CI, 0.99–1.05) for β-carotene recipients compared with nonrecipients. α-Tocopherol decreased post-trial prostate cancer mortality (RR, 0.84; 95% CI, 0.70–0.99), whereas β-carotene increased it (RR, 1.20; 95% CI, 1.01–1.42). In conclusion, supplementation with α-tocopherol and β-carotene appeared to have no late effects on cancer incidence. The preventive effect of moderate-dose α-tocopherol on prostate cancer continued several years post-trial and resulted in lower prostate cancer mortality.