JAMA Dermatol. 2019 Jul 31. Epub 2019 Jul 31. PMID: 31365038
Association of Vitamin A Intake With Cutaneous Squamous Cell Carcinoma Risk in the United States.
Importance: Retinoids are bioactive forms of vitamin A that are essential in the maintenance of epithelial maturation and differentiation. Synthetic retinoids are used in chemoprevention of skin cancer among high-risk populations with potential adverse effects. Epidemiologic data on vitamin A intake and risk of cutaneous squamous cell carcinoma (SCC) are limited.Objective: To examine whether vitamin A intake is associated with a reduction in SCC risk.Design, Settings, and Participants: This cohort study prospectively examined intake of vitamin A and carotenoids and SCC risk in the Nurses' Health Study (1984-2012) and the Health Professionals Follow-up Study (1986-2012). Diet was assessed repeatedly. Incident SCC was confirmed by pathologic reports. Data analysis was performed from June 21, 2017, to December 4, 2018.Exposures: Intakes of vitamin A, retinol, and carotenoids.Main Outcomes and Measures: Incident SCC. Cox proportional hazards regression models were used to compute cohort-specific hazard ratios (HRs) and 95% CIs. Pooled HRs of the cohort-specific results were calculated.Results: A total of 3978 SCC cases in 75 170 women in the Nurses' Health Study (mean [SD] age, 50.4 [7.2] years) and 48 400 men in the Health Professionals Follow-up Study (mean [SD] age, 54.3 [9.9] years) were documented. Higher total vitamin A was associated with a reduction in SCC risk; with quintile 1 as the reference, the pooledmultivariate HRs for the increasing quintiles of vitamin A intake were 0.97 (95% CI, 0.87-1.07) for quintile 2, 0.97 (95% CI, 0.80-1.17) for quintile 3, 0.93 (95% CI, 0.84-1.03) for quintile 4, and 0.83 (95% CI, 0.75-0.93) for quintile 5 (P