title: Vitamin A and retinoid derivatives for lung cancer: a systematic review and meta analysis.
abstract: BACKGROUND
  Despite reported antiproliferative activity of vitamin A and its common use for cancer, there is no comprehensive synthesis of its safety and efficacy in lung cancers. To address this issue we conducted a systematic review of the safety and efficacy of vitamin A for the treatment and prevention of lung cancers.
  
  
  RESULTS
  Two independent reviewers searched six electronic databases from inception to July 2009 for clinical, observational, and preclinical evidence pertaining to the safety and efficacy of vitamin A and related retinoids for lung cancers. 248 studies were included for full review and analysis. Five RCTs assessed treatment of lung cancers, three assessed primary prevention, and three looked at secondary prevention of lung cancers. Five surrogate studies, 26 phase I/II, 32 observational, and 67 preclinical studies were also included. 107 studies were included for interactions between vitamin A and chemo- or radiation-therapy. Although some studies demonstrated benefits, there was insufficient evidence overall to support the use of vitamin A or related retinoids for the treatment or prevention of lung cancers. Retinyl palmitate combined with beta carotene increased risk of lung cancer in smokers in the large CARET trial. Pooling of three studies pertaining to treatment and three studies on secondary prevention revealed no significant effects on response rate, second primary tumor, recurrence, 5-year survival, and mortality. There was a small improvement in event free survival associated with vitamin A compared to controls, RR 1.24 (95% CI 1.13-1.35). The synthetic rexinoid bexarotene increased survival significantly among a subset of patients in two RCTs (p<0.014, <0.087).
  
  
  CONCLUSIONS
  There is a lack of evidence to support the use of naturally occurring retinoids for the treatment and prevention of lung cancers. The rexinoid bexarotene may hold promise for use among a subset of patients, and deserves further study.
authors: Department of Research and Epidemiology, The Canadian College of Naturopathic Medicine, Toronto, Ontario, Canada.
authors: Heidi
authors: H
authors: Fritz
authors: Deborah
authors: D
authors: Kennedy
authors: Dean
authors: D
authors: Fergusson
authors: Rochelle
authors: R
authors: Fernandes
authors: Steve
authors: S
authors: Doucette
authors: Kieran
authors: K
authors: Cooley
authors: Andrew
authors: A
authors: Seely
authors: Stephen
authors: S
authors: Sagar
authors: Raimond
authors: R
authors: Wong
authors: Dugald
authors: D
authors: Seely
mesh_terms: D000818:Animals; D004224:Diterpenes; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D012176:Retinoids / Q000009:adverse effects / Q000627:therapeutic use*; D000084562:Retinyl Esters; D014801:Vitamin A / Q000009:adverse effects / Q000031:analogs & derivatives / Q000627:therapeutic use*; D019207:beta Carotene / Q000009:adverse effects / Q000627:therapeutic use
chemical_list: D004224:Diterpenes; D012176:Retinoids; D000084562:Retinyl Esters; D019207:beta Carotene; D014801:Vitamin A; C014794:retinol palmitate