Associations between dietary and supplemental vitamin A intake and melanoma and non-melanoma skin cancer.

Background: Cutaneous melanoma (CM) and non-melanoma skin cancer (NMSC) are rising in postmenopausal women. Although high doses of oral vitamin A reduce NMSC risk in high-risk patients, the role of vitamin A in preventing skin cancer in this group remains unexplored.

Objectives: To determine the association between total (dietary and supplemental) vitamin A and risk of CM and NMSC in postmenopausal women.

Methods: This retrospective cohort study included 52 877 White women from the Women's Health Initiative cohort, spanning from 1993 to 2019. Exposures were intake of total vitamin A, retinol and provitamin A carotenoids. Cox proportional hazard models estimated hazard ratios for overall CM incidence, whereas logistic regression determined odds ratios (ORs) for melanoma subtypes and NMSC.

Results: 1154 cases of CM and 9085 cases of NMSC were identified over an average follow-up period of 17.8 years (SD 6.7). No associations were identified between total vitamin A intake and melanoma risk. Higher dietary vitamin A intake was associated with higher risk of NMSC (OR of 3rd vs. 1st tertile of dietary intake = 1.12, 95% confidence interval [CI] [1.06, 1.18]), as was dietary beta-cryptoxanthin, a provitamin A carotenoid (OR of 3rd vs. 1st tertile of dietary intake = 1.22, 95% CI [1.15, 1.29]); these results were consistent across both age- and fully adjusted regression models.

Conclusions: Total vitamin A intake was not associated with lower risk of CM or NMSC. Dietary vitamin A and beta-cryptoxanthin intake were associated with a slightly higher risk of NMSC in postmenopausal women.