title: Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease.
abstract: BACKGROUND
  Lung cancer and cardiovascular disease are major causes of death in the United States. It has been proposed that carotenoids and retinoids are agents that may prevent these disorders.
  
  
  METHODS
  We conducted a multicenter, randomized, double-blind, placebo-controlled primary prevention trial -- the Beta Carotene and Retinol Efficacy Trial -- involving a total of 18,314 smokers, former smokers, and workers exposed to asbestos. The effects of a combination of 30 mg of beta carotene per day and 25,000 IU of retinol (vitamin A) in the form of retinyl palmitate per day on the primary end point, the incidence of lung cancer, were compared with those of placebo.
  
  
  RESULTS
  A total of 388 new cases of lung cancer were diagnosed during the 73,135 person-years of follow-up (mean length of follow-up, 4.0 years). The active-treatment group had a relative risk of lung cancer of 1.28 (95 percent confidence interval, 1.04 to 1.57; P=0.02), as compared with the placebo group. There were no statistically significant differences in the risks of other types of cancer. In the active-treatment group, the relative risk of death from any cause was 1.17 (95 percent confidence interval, 1.03 to 1.33); of death from lung cancer, 1.46 (95 percent confidence interval, 1.07 to 2.00); and of death from cardiovascular disease, 1.26 (95 percent confidence interval, 0.99 to 1.61). On the basis of these findings, the randomized trial was stopped 21 months earlier than planned; follow-up will continue for another 5 years.
  
  
  CONCLUSIONS
  After an average of four years of supplementation, the combination of beta carotene and vitamin A had no benefit and may have had an adverse effect on the incidence of lung cancer and on the risk of death from lung cancer, cardiovascular disease, and any cause in smokers and workers exposed to asbestos.
authors.affiliation: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98104, USA.
authors.forename: G S
authors.initials: GS
authors.lastname: Omenn
authors.forename: G E
authors.initials: GE
authors.lastname: Goodman
authors.forename: M D
authors.initials: MD
authors.lastname: Thornquist
authors.forename: J
authors.initials: J
authors.lastname: Balmes
authors.forename: M R
authors.initials: MR
authors.lastname: Cullen
authors.forename: A
authors.initials: A
authors.lastname: Glass
authors.forename: J P
authors.initials: JP
authors.lastname: Keogh
authors.forename: F L
authors.initials: FL
authors.lastname: Meyskens
authors.forename: B
authors.initials: B
authors.lastname: Valanis
authors.forename: J H
authors.initials: JH
authors.lastname: Williams
authors.forename: S
authors.initials: S
authors.lastname: Barnhart
authors.forename: S
authors.initials: S
authors.lastname: Hammar
mesh_terms: D000368:Aged; D000975:Antioxidants / Q000009:adverse effects / Q000627:therapeutic use*; D001194:Asbestos / Q000009:adverse effects; D002318:Cardiovascular Diseases / Q000401:mortality / Q000517:prevention & control*; D002338:Carotenoids / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000139:chemically induced / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D009026:Mortality; D016273:Occupational Exposure; D012306:Risk; D012907:Smoking / Q000009:adverse effects; D014801:Vitamin A / Q000009:adverse effects / Q000627:therapeutic use*; D019207:beta Carotene
chemical_list: D000975:Antioxidants; D019207:beta Carotene; D014801:Vitamin A; D001194:Asbestos; D002338:Carotenoids