Effects of α-tocopherol and β-carotene supplementation on cancer incidence and mortality : 18-Year postintervention follow-up of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study
Menée sur une cohorte de 25 563 hommes (durée de suivi : 18 ans), cette étude finlandaise évalue les effets d'une supplémentation en α-tocophérol ou β-carotène sur le risque de cancer et la mortalité par cancer de la prostate
In the Alpha-Tocopherol, Beta-Carotene Cancer Prevention 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 postintervention 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
8 years postintervention. 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.