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Alpha-Tocopherol and beta-carotene supplements and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: effects of base-line characteristics and study compliance.

Abstract

BACKGROUND

Experimental and epidemiologic investigations suggest that alpha-tocopherol (the most prevalent chemical form of vitamin E found in vegetable oils, seeds, grains, nuts, and other foods) and beta-carotene (a plant pigment and major precursor of vitamin A found in many yellow, orange, and dark-green, leafy vegetables and some fruit) might reduce the risk of cancer, particularly lung cancer. The initial findings of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC Study) indicated, however, that lung cancer incidence was increased among participants who received beta-carotene as a supplement. Similar results were recently reported by the Beta-Carotene and Retinol Efficacy Trial (CARET), which tested a combination of beta-carotene and vitamin A.

PURPOSE

We examined the effects of alpha-tocopherol and beta-carotene supplementation on the incidence of lung cancer across subgroups of participants in the ATBC Study defined by base-line characteristics (e.g., age, number of cigarettes smoked, dietary or serum vitamin status, and alcohol consumption), by study compliance, and in relation to clinical factors, such as disease stage and histologic type. Our primary purpose was to determine whether the pattern of intervention effects across subgroups could facilitate further interpretation of the main ATBC Study results and shed light on potential mechanisms of action and relevance to other populations.

METHODS

A total of 29,133 men aged 50-69 years who smoked five or more cigarettes daily were randomly assigned to receive alpha-tocopherol (50 mg), beta-carotene (20 mg), alpha-tocopherol and beta-carotene, or a placebo daily for 5-8 years (median, 6.1 years). Data regarding smoking and other risk factors for lung cancer and dietary factors were obtained at study entry, along with measurements of serum levels of alpha-tocopherol and beta-carotene. Incident cases of lung cancer (n = 894) were identified through the Finnish Cancer Registry and death certificates. Each lung cancer diagnosis was independently confirmed, and histology or cytology was available for 94% of the cases. Intervention effects were evaluated by use of survival analysis and proportional hazards models. All P values were derived from two-sided statistical tests.

RESULTS

No overall effect was observed for lung cancer from alpha-tocopherol supplementation (relative risk [RR] = 0.99; 95% confidence interval [CI] = 0.87-1.13; P = .86, logrank test). beta-Carotene supplementation was associated with increased lung cancer risk (RR = 1.16; 95% CI = 1.02-1.33; P = .02, logrank test). The beta-carotene effect appeared stronger, but not substantially different, in participants who smoked at least 20 cigarettes daily (RR = 1.25; 95% CI = 1.07-1.46) compared with those who smoked five to 19 cigarettes daily (RR = 0.97; 95% CI = 0.76-1.23) and in those with a higher alcohol intake (> or = 11 g of ethanol/day [just under one drink per day]; RR = 1.35; 95% CI = 1.01-1.81) compared with those with a lower intake (RR = 1.03; 95% CI = 0.85-1.24).

CONCLUSIONS

Supplementation with alpha-tocopherol or beta-carotene does not prevent lung cancer in older men who smoke. beta-Carotene supplementation at pharmacologic levels may modestly increase lung cancer incidence in cigarette smokers, and this effect may be associated with heavier smoking and higher alcohol intake.

IMPLICATIONS

While the most direct way to reduce lung cancer risk is not to smoke tobacco, smokers should avoid high-dose beta-carotene supplementation.

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  • Publisher Full Text
  • Authors+Show Affiliations

    ,

    Division of Cancer Prevention and Control, National Cancer Institute, Bethesda, MD 20892-7326, USA.

    , , , , , , , , , , , , , , , , , , , , ,

    Source

    Journal of the National Cancer Institute 88:21 1996 Nov 06 pg 1560-70

    MeSH

    Age Factors
    Aged
    Alcohol Drinking
    Anticarcinogenic Agents
    Antioxidants
    Carcinogens
    Food, Fortified
    Humans
    Incidence
    Lung Neoplasms
    Male
    Middle Aged
    Multivariate Analysis
    Patient Compliance
    Proportional Hazards Models
    Risk
    Risk Factors
    Smoking
    Vitamin E
    beta Carotene

    Pub Type(s)

    Clinical Trial
    Journal Article
    Randomized Controlled Trial
    Research Support, U.S. Gov't, P.H.S.

    Language

    eng

    PubMed ID

    8901854

    Citation

    Albanes, D, et al. "Alpha-Tocopherol and Beta-carotene Supplements and Lung Cancer Incidence in the Alpha-tocopherol, Beta-carotene Cancer Prevention Study: Effects of Base-line Characteristics and Study Compliance." Journal of the National Cancer Institute, vol. 88, no. 21, 1996, pp. 1560-70.
    Albanes D, Heinonen OP, Taylor PR, et al. Alpha-Tocopherol and beta-carotene supplements and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: effects of base-line characteristics and study compliance. J Natl Cancer Inst. 1996;88(21):1560-70.
    Albanes, D., Heinonen, O. P., Taylor, P. R., Virtamo, J., Edwards, B. K., Rautalahti, M., ... Huttunen, J. K. (1996). Alpha-Tocopherol and beta-carotene supplements and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: effects of base-line characteristics and study compliance. Journal of the National Cancer Institute, 88(21), pp. 1560-70.
    Albanes D, et al. Alpha-Tocopherol and Beta-carotene Supplements and Lung Cancer Incidence in the Alpha-tocopherol, Beta-carotene Cancer Prevention Study: Effects of Base-line Characteristics and Study Compliance. J Natl Cancer Inst. 1996 Nov 6;88(21):1560-70. PubMed PMID: 8901854.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Alpha-Tocopherol and beta-carotene supplements and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: effects of base-line characteristics and study compliance. AU - Albanes,D, AU - Heinonen,O P, AU - Taylor,P R, AU - Virtamo,J, AU - Edwards,B K, AU - Rautalahti,M, AU - Hartman,A M, AU - Palmgren,J, AU - Freedman,L S, AU - Haapakoski,J, AU - Barrett,M J, AU - Pietinen,P, AU - Malila,N, AU - Tala,E, AU - Liippo,K, AU - Salomaa,E R, AU - Tangrea,J A, AU - Teppo,L, AU - Askin,F B, AU - Taskinen,E, AU - Erozan,Y, AU - Greenwald,P, AU - Huttunen,J K, PY - 1996/11/6/pubmed PY - 1996/11/6/medline PY - 1996/11/6/entrez SP - 1560 EP - 70 JF - Journal of the National Cancer Institute JO - J. Natl. Cancer Inst. VL - 88 IS - 21 N2 - BACKGROUND: Experimental and epidemiologic investigations suggest that alpha-tocopherol (the most prevalent chemical form of vitamin E found in vegetable oils, seeds, grains, nuts, and other foods) and beta-carotene (a plant pigment and major precursor of vitamin A found in many yellow, orange, and dark-green, leafy vegetables and some fruit) might reduce the risk of cancer, particularly lung cancer. The initial findings of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC Study) indicated, however, that lung cancer incidence was increased among participants who received beta-carotene as a supplement. Similar results were recently reported by the Beta-Carotene and Retinol Efficacy Trial (CARET), which tested a combination of beta-carotene and vitamin A. PURPOSE: We examined the effects of alpha-tocopherol and beta-carotene supplementation on the incidence of lung cancer across subgroups of participants in the ATBC Study defined by base-line characteristics (e.g., age, number of cigarettes smoked, dietary or serum vitamin status, and alcohol consumption), by study compliance, and in relation to clinical factors, such as disease stage and histologic type. Our primary purpose was to determine whether the pattern of intervention effects across subgroups could facilitate further interpretation of the main ATBC Study results and shed light on potential mechanisms of action and relevance to other populations. METHODS: A total of 29,133 men aged 50-69 years who smoked five or more cigarettes daily were randomly assigned to receive alpha-tocopherol (50 mg), beta-carotene (20 mg), alpha-tocopherol and beta-carotene, or a placebo daily for 5-8 years (median, 6.1 years). Data regarding smoking and other risk factors for lung cancer and dietary factors were obtained at study entry, along with measurements of serum levels of alpha-tocopherol and beta-carotene. Incident cases of lung cancer (n = 894) were identified through the Finnish Cancer Registry and death certificates. Each lung cancer diagnosis was independently confirmed, and histology or cytology was available for 94% of the cases. Intervention effects were evaluated by use of survival analysis and proportional hazards models. All P values were derived from two-sided statistical tests. RESULTS: No overall effect was observed for lung cancer from alpha-tocopherol supplementation (relative risk [RR] = 0.99; 95% confidence interval [CI] = 0.87-1.13; P = .86, logrank test). beta-Carotene supplementation was associated with increased lung cancer risk (RR = 1.16; 95% CI = 1.02-1.33; P = .02, logrank test). The beta-carotene effect appeared stronger, but not substantially different, in participants who smoked at least 20 cigarettes daily (RR = 1.25; 95% CI = 1.07-1.46) compared with those who smoked five to 19 cigarettes daily (RR = 0.97; 95% CI = 0.76-1.23) and in those with a higher alcohol intake (> or = 11 g of ethanol/day [just under one drink per day]; RR = 1.35; 95% CI = 1.01-1.81) compared with those with a lower intake (RR = 1.03; 95% CI = 0.85-1.24). CONCLUSIONS: Supplementation with alpha-tocopherol or beta-carotene does not prevent lung cancer in older men who smoke. beta-Carotene supplementation at pharmacologic levels may modestly increase lung cancer incidence in cigarette smokers, and this effect may be associated with heavier smoking and higher alcohol intake. IMPLICATIONS: While the most direct way to reduce lung cancer risk is not to smoke tobacco, smokers should avoid high-dose beta-carotene supplementation. SN - 0027-8874 UR - https://www.unboundmedicine.com/medline/citation/8901854/full_citation L2 - https://academic.oup.com/jnci/article-lookup/doi/10.1093/jnci/88.21.1560 DB - PRIME DP - Unbound Medicine ER -