Positive Health Online

Abstract

WRIGHT and others, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, Maryland, USA,  mewright@uic.ed, have conducted a large randomized controlled trial of antioxidant supplementation in the prevention of cancers of the mouth, oesophagus, larynx and pharynx.

Background

Although smoking and alcohol consumption are the major risk factors for upper aerodigestive tract cancers, observational studies indicate a protective role for fruits, vegetables, and antioxidant nutrients. The aim of this study was to examine whether daily supplementation with vitamin E and/or beta-carotene reduced the incidence of or mortality from oral/pharyngeal, oesophageal, and laryngeal cancers.

Methodology

In the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) study, a double-blind, placebo-controlled primary prevention trial conducted in Finland, a total of 29,133 male smokers, aged 50-69 years and free of cancer at baseline, were randomized in a 2 x 2 factorial design to the supplementation regimen for 5-8 years (median, 6.1 years). The supplementation consisted of 50 mg vitamin E and / or 20 mg beta-carotene daily, or placebo. Incident cancers of the oral cavity and pharynx (n = 65), oesophagus (n = 24), and larynx (n = 56) were identified through the Finnish Cancer Registry. Intervention effects were assessed using survival analysis and proportional hazards models.

Results

There was no effect of either agent on the overall incidence of any upper aerodigestive tract cancer. For larynx, however, exploratory subgroup analyses were suggestive of a protective effect of beta-carotene supplementation on the incidence of early stage malignancies (stage I, relative risk, 0.28). Neither agent affected mortality from these neoplasms.

Conclusion

The results do not provide support for a protective effect of vitamin E or beta-carotene supplementation on upper aerodigestive tract cancers, although beta-carotene supplementation may impact the incidence of some subtypes of laryngeal tumours.

References

Wright ME et al. Effects of alpha-tocopherol and beta-carotene supplementation on upper aerodigestive tract cancers in a large, randomized controlled trial. Cancer 109 (5): 891-98, Mar 1, 2007.