Positive Health Online

Abstract

VAN POPPEL and colleagues, TNO Nutrition, Zeist, the Netherlands write that the use of biomarkers is a promising approach to the study of human cancer risk and that bronchial metaplasia in sputum cytology could be a marker for potential premalignancy which could be applied to population studies.

Background

Methodology

The authors performed a randomised controlled trial in smokers regarding the effect of 14 weeks beta-carotene supplementation (20 mg/ day) upon DNA markers damage. The authors evaluated the application of sputum cytology and evaluated the effect of beta-carotene.

Results

From the 150 potential participants 75 were ineligible either because they failed to produce sputum or samples were unsatisfactory. The eligible group was older (41 vs 37 years) and had smoked longer (23 vs 19 years) and had similar cigarette consumption (mean of 21/days) and plasma cotinine levels. Bronchial metaplasia was graded in seven categories only 15% (11 people) showed minor or mild atypia at entry to the study. There was no significant correlation between before and following treatment final metaplasia scores in the beta-carotene or placebo group. The initial metaplasia scores were somewhat higher in the beta-carotene group than in the placebo group final metaplasia scores were similar in both groups and there was no decrease in metaplasia scores in the beta-carotene group.

Conclusion

Sputum cytology may not yet be a readily applicable marker in studies of healthy asymptomatic populations as many smokers dont spontaneously produce sputum, more severe lesions are rare and there are large variations over time in minor lesions. Therefore, preliminary evidence that beta-carotene has no influence needs to be interpreted with care.

References

van Poppel G et al. The effect of beta-carotene on sputum cytology in smokers: a preliminary study. Eur J Cancer Prev 6(3): 294-9. Jun 1997.

Comment

Definitive evidence in humans that specific nutritional elements have a direct effect upon cancer treatment has been hard to come by, particularly with beta-carotene. This is in marked contrast with animal studies where beta-carotene has been shown to block the development of cancer lesions induced via a number of chemical carcinogenic agents. Of course, we cant control human behaviour to the extent that we can define the diet of laboratory animals. People over a lifetime change their diet, lifestyle and environment markedly. Who can say when a cancer started and when it progressed? However, there are an abundance of promising cancer treatment protocols in use today using nutrients such as vitamins A and C, beta-carotene, fatty acids and other co-factors such as Coenzyme Q10.