Alpha-tocopherol, Beta-Carotene Lung Cancer Prevention Study - ATBC

Jul 09, 2003
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Date Published:
01/01/1996
Date Updated:
07/09/2003
Original Posted Date:
07/09/2003
References

Description:

Anti-oxidant therapy for primary prevention of lung and other cancers.

Hypothesis:

AT and BC, both agents with strong antioxidant properties and low toxicity, protect against lung and other cancers.

Study Design

Study Design:

Patients Screened: 224,377
Patients Enrolled: 29,133
Mean Follow Up: 6.1 years
Mean Patient Age: 57.1
Female: 0

Patient Populations:

Male
50 to 59 years of age
Smoke 5 or more cigarettes per day at study entry
Reside within the study region (southwestern Finland)
Willing to participate (written consent)

Exclusions:

Proven malignancy other than nonmelanoma skin cancer or carcinoma in situ
Severe angina on exertion
Chronic renal insufficiency
Cirrhosis of liver
Chronic alcoholism
Receiving anticoagulant therapy
Other medical problems that might limit participation for 6 years, such as psychiatric disorder or physical disability
Current use of supplements containing vitamin E >20 mg/day) or vitamin A (>20,000 IU/day) or BC (>6 mg/day)

Primary Endpoints:

Lung cancer

Secondary Endpoints:

Other cancers

Drug/Procedures Used:

AT: 50 mg qd
BC: 20 mg qd

Principal Findings:

Capsule compliance was high (median = 99%).

Beta carotene treatment did not result in a decrease in cancer at any of the major sites, but rather in an increase at several sites, most notably lung, prostate, and stomach (number of cases 474 vs. 402; 138 vs. 112; 70 vs. 56 respectively).

The vitamin E group had fewer incident cancers of the prostate and colorectum compared with the group not receiving vitamin E (number of cases 99 vs. 151 and 68 vs. 81, respectively), but more cancers of the stomach (70 vs. 56).

In contrast to these intervention-based findings for beta-carotene and vitamin E supplements, the authors observed lower lung cancer rates in men with higher amounts of both serum and dietary beta-carotene and vitamin E at baseline.

For lung cancer, 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) and in those with a higher alcohol intake (> or = 11g of ethanol/day [just under one drink per day]; RR = 1.35; 95% CI = 1.01-1.81).

Interpretation:

This large trial of male smokers in Finland raises the possibility that supplementation with beta-carotene and vitamin E has both beneficial and harmful effects in certain populations. 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. Longer observation of these subjects is essential, as is comparison with other ongoing large prevention trials.

References:

1. Ann Epid 1994; 4: 1-10. Design and baseline results
2. Am J Clin Nutr 1996; 62(suppl):1427S-1430S. Final results
3. J Nat Cancer Inst 1996;88:1560-70, 1996 Subgroup analysis

Keywords: Vitamins, Vitamin E, beta Carotene, alpha-Tocopherol, Dietary Supplements, Ethanol, Lung Neoplasms, Primary Prevention, Smoking, Prostate


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