title: Is there a role for oral or intravenous ascorbate (vitamin C) in treating patients with cancer? A systematic review.
abstract: BACKGROUND
  Many cancer patients receive supplemental ascorbate (vitamin C) in the belief that it synergizes the anticancer effects of chemotherapy and reduces its toxicity.
  
  
  METHODS
  A systematic review was performed to evaluate the antitumor effects and toxicity of ascorbate treatment. Medline (1946 to March 2014), EMBASE (1947 to March 2014), and the Cochrane central register (1993 to March 2014) were searched for randomized and observational studies.
  
  
  RESULTS
  Of 696 identified records, 61 full-text articles were screened and 34 were included. In total, 5 randomized controlled trials (RCTs) (n = 322), 12 phase I/II trials (n = 287), 6 observational studies (n = 7,599), and 11 case reports (n = 267) were identified. Because of study heterogeneity, no meta-analyses were performed. No RCTs reported any statistically significant improvements in overall or progression-free survival or reduced toxicity with ascorbate relative to control arm. Evidence for ascorbate's antitumor effects was limited to case reports and observational and uncontrolled studies.
  
  
  CONCLUSIONS
  There is no high-quality evidence to suggest that ascorbate supplementation in cancer patients either enhances the antitumor effects of chemotherapy or reduces its toxicity. Given the high financial and time costs to patients of this treatment, high-quality placebo-controlled trials are needed.
authors.affiliation: Division of Medical Oncology, Ottawa Hospital Cancer Centre, and Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada cjacobs@toh.on.ca.
authors.forename: Carmel
authors.initials: C
authors.lastname: Jacobs
authors.affiliation: Division of Medical Oncology, Ottawa Hospital Cancer Centre, and Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Brian
authors.initials: B
authors.lastname: Hutton
authors.affiliation: Division of Medical Oncology, Ottawa Hospital Cancer Centre, and Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Terry
authors.initials: T
authors.lastname: Ng
authors.affiliation: Division of Medical Oncology, Ottawa Hospital Cancer Centre, and Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Risa
authors.initials: R
authors.lastname: Shorr
authors.affiliation: Division of Medical Oncology, Ottawa Hospital Cancer Centre, and Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Clemons
mesh_terms: D001205:Ascorbic Acid / Q000008:administration & dosage*; D019587:Dietary Supplements; D018572:Disease-Free Survival; D006801:Humans; D009369:Neoplasms / Q000178:diet therapy* / Q000473:pathology; D016032:Randomized Controlled Trials as Topic
chemical_list: D001205:Ascorbic Acid
keywords: Ascorbate; Cancer; Chemotherapy; Quality of life; Vitamin C