Effects of supplemental alpha-tocopherol and beta-carotene on urinary tract cancer: incidence and mortality in a controlled trial (Finland).
Maneno muhimu
Kikemikali
OBJECTIVE
Epidemiological studies have suggested a protective effect of vegetables and fruits on urinary tract cancer but the possible protective nutrients are unknown. We studied the effect of alpha-tocopherol (a form of vitamin E) and beta-carotene supplementation on urinary tract cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study.
METHODS
A total of 29,133 male smokers aged 50-69 years from southwestern Finland were randomly assigned to receive alpha-tocopherol (50 mg), beta-carotene (20 mg), both agents, or a placebo daily for 5-8 years (median 6.1 years). Incident urothelial cancers (bladder, ureter, and renal pelvis; n = 169) and renal cell cancers (n = 102) were identified through the nationwide cancer registry. The diagnoses were centrally confirmed by review of medical records and pathology specimens. The supplementation effects were estimated using a proportional hazards model.
RESULTS
Neither alpha-tocopherol nor beta-carotene affected the incidence of urothelial cancer, relative risk 1.1 (95% confidence interval (CI) 0.8-1.5) and 1.0 (95% CI 0.7-1.3), respectively, or the incidence of renal cell cancer, relative risk 1.1 (95% CI 0.7-1.6) and 0.8 (95% CI 0.6-1.3), respectively.
CONCLUSIONS
Long-term supplementation with alpha-tocopherol and beta-carotene has no preventive effect on urinary tract cancers in middle-aged male smokers.
