Context In the Finnish Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC)
Study, α-tocopherol supplementation decreased prostate cancer incidence,
whereas β-carotene increased the risk of lung cancer and total mortality.
Postintervention follow-up provides information regarding duration of the
intervention effects and may reveal potential late effects of these antioxidants.
Objective To analyze postintervention effects of α-tocopherol and β-carotene
on cancer incidence and total and cause-specific mortality.
Design, Setting, and Participants Postintervention follow-up assessment of cancer incidence and cause-specific
mortality (6 years [May 1, 1993-April 30, 1999]) and total mortality (8 years
[May 1, 1993-April 30, 2001]) of 25 563 men. In the ATBC Study, 29 133
male smokers aged 50 to 69 years received α-tocopherol (50 mg), β-carotene
(20 mg), both agents, or placebo daily for 5 to 8 years. End point information
was obtained from the Finnish Cancer Registry and the Register of Causes of
Death. Cancer cases were confirmed through medical record review.
Main Outcome Measures Site-specific cancer incidence and total and cause-specific mortality
and calendar time-specific risk for lung cancer incidence and total mortality.
Results Overall posttrial relative risk (RR) for lung cancer incidence (n =
1037) was 1.06 (95% confidence interval [CI], 0.94-1.20) among recipients
of β-carotene compared with nonrecipients. For prostate cancer incidence
(n = 672), the RR was 0.88 (95% CI, 0.76-1.03) for participants receiving α-tocopherol
compared with nonrecipients. No late preventive effects on other cancers were
observed for either supplement. There were 7261 individuals who died by April
30, 2001, during the posttrial follow-up period; the RR was 1.01 (95% CI,
0.96-1.05) for α-tocopherol recipients vs nonrecipients and 1.07 (95%
CI, 1.02-1.12) for β-carotene recipients vs nonrecipients. Regarding
duration of intervention effects and potential late effects, the excess risk
for β-carotene recipients was no longer evident 4 to 6 years after ending
the intervention and was primarily due to cardiovascular diseases.
Conclusions The beneficial and adverse effects of supplemental α-tocopherol
and β-carotene disappeared during postintervention follow-up. The preventive
effects of α-tocopherol on prostate cancer require confirmation in other
trials. Smokers should avoid β-carotene supplementation.