title: Calcium plus vitamin D supplementation and the risk of nonmelanoma and melanoma skin cancer: post hoc analyses of the women's health initiative randomized controlled trial.
abstract: OBJECTIVE
  In light of inverse relationships reported in observational studies of vitamin D intake and serum 25-hydroxyvitamin D levels with risk of nonmelanoma skin cancer (NMSC) and melanoma, we evaluated the effects of vitamin D combined with calcium supplementation on skin cancer in a randomized placebo-controlled trial.
  
  
  METHODS
  Postmenopausal women age 50 to 79 years (N = 36,282) enrolled onto the Women's Health Initiative (WHI) calcium/vitamin D clinical trial were randomly assigned to receive 1,000 mg of elemental calcium plus 400 IU of vitamin D3 (CaD) daily or placebo for a mean follow-up period of 7.0 years. NMSC and melanoma skin cancers were ascertained by annual self-report; melanoma skin cancers underwent physician adjudication.
  
  
  RESULTS
  Neither incident NMSC nor melanoma rates differed between treatment (hazard ratio [HR], 1.02; 95% CI, 0.95 to 1.07) and placebo groups (HR, 0.86; 95% CI, 0.64 to 1.16). In subgroup analyses, women with history of NMSC assigned to CaD had a reduced risk of melanoma versus those receiving placebo (HR, 0.43; 95% CI, 0.21 to 0.90; P(interaction) = .038), which was not observed in women without history of NMSC.
  
  
  CONCLUSIONS
  Vitamin D supplementation at a relatively low dose plus calcium did not reduce the overall incidence of NMSC or melanoma. However, in women with history of NMSC, CaD supplementation reduced melanoma risk, suggesting a potential role for calcium and vitamin D supplements in this high-risk group. Results from this post hoc subgroup analysis should be interpreted with caution but warrant additional investigation.
authors.affiliation: Department of Dermatology, Stanford University School of Medicine, 450 Broadway, Pavilion C, MC 5334, Redwood City, CA, USA. tangy@stanford.edu
authors.forename: Jean Y
authors.initials: JY
authors.lastname: Tang
authors.forename: Teresa
authors.initials: T
authors.lastname: Fu
authors.forename: Erin
authors.initials: E
authors.lastname: Leblanc
authors.forename: Joann E
authors.initials: JE
authors.lastname: Manson
authors.forename: David
authors.initials: D
authors.lastname: Feldman
authors.forename: Eleni
authors.initials: E
authors.lastname: Linos
authors.forename: Mara Z
authors.initials: MZ
authors.lastname: Vitolins
authors.forename: Nathalie C
authors.initials: NC
authors.lastname: Zeitouni
authors.forename: Joseph
authors.initials: J
authors.lastname: Larson
authors.forename: Marcia L
authors.initials: ML
authors.lastname: Stefanick
mesh_terms: D000368:Aged; D002136:Calcium, Dietary / Q000008:administration & dosage*; D002762:Cholecalciferol / Q000008:administration & dosage*; D015986:Confounding Factors, Epidemiologic; D019587:Dietary Supplements; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008545:Melanoma / Q000453:epidemiology* / Q000517:prevention & control*; D008875:Middle Aged; D016017:Odds Ratio; D017698:Postmenopause; D012107:Research Design; D018570:Risk Assessment; D012307:Risk Factors; D012878:Skin Neoplasms / Q000453:epidemiology* / Q000517:prevention & control*; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D016387:Women's Health
chemical_list: D002136:Calcium, Dietary; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D