25-Hydroxyvitamin D status, vitamin D intake, and skin cancer risk: a systematic review and dose–response meta-analysis of prospective studies
What this study found
Circulating 25(OH)D levels are positively associated with melanoma and keratinocyte cancer (KC) risk. RR per 30 nmol/L increase: melanoma 1.42 (1.17-1.72); KC 1.30 (1.13-1.49). Highest vs lowest levels: melanoma 1.60 (1.18-2.17); KC 1.82 (1.49-2.21). Within KC, BCC per 30 nmol/L increase 1.41 (1.19-1.67); SCC per 30 nmol/L increase 1.57 (0.64-3.86). Vitamin D intake from diet, supplements, and total is not associated with melanoma or SCC; however dietary vitamin D shows a small positive association with BCC risk (per 100 IU/day: 1.04 [1.02-1.06]); supplemental and total vitamin D show no…
- Study & population
- Prospective cohort studies; 13 cohorts included; melanoma: 1,644 cases among 241,893 participants; KC: 7,485 cases among 249,108 participants; studies conducted in North America (7 studies), Europe (5), and Australia (1); age and sex details not reported; no dosing information.
- Key limitation
- Observational design; reliance on a single baseline 25(OH)D measurement; potential reverse causation and residual confounding (notably sun exposure); risk of bias among included studies (several serious); heterogeneity across studies; limited data for nonlinear dose-response analyses and subgroup analyses; limited…
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Open PDFOriginal abstract
Sun exposure is a major environmental risk factor for skin cancers and is also an important source of vitamin D. However, while experimental evidence suggests that vitamin D may have a protective effect on skin cancer risk, epidemiologic studies investigating the influence of 25-hydroxyvitamin D (25(OH)D) level and/or vitamin D intake on skin cancer risk are conflicting. A systematic review and dose–response meta-analyses of prospective studies was conducted to clarify these associations. Relevant studies were identified by searching the PubMed database up to 30th August 2019. Random effects dose–response meta-analyses were used to estimate summary relative risks (SRRs) and 95% confidence intervals (CIs). Overall, thirteen prospective studies were included. Circulating level of 25(OH)D was associated with higher risks of melanoma (SRR (95% CI) per 30 nmol = 1.42 (1.17–1.72)) and keratinocyte cancer (KC) (SRR (95% CI) per 30 nmol/L = 1.30 (1.13–1.49)). The SRR (95% CI) per 30 nmol/L increase in 25(OH) D level was 1.41 (1.19–1.67), and 1.57 (0.64–3.86), for basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs), respectively. However, while we found that vitamin D intake (from diet, supplemental and total) was not associated with risks of melanoma and SCC, vitamin D intake was associated with slightly increased BCC risk, albeit with no heterogeneity across skin cancer type. This meta-analysis suggests positive associations between circulating 25(OH)D level and risk of melanoma and KC, however, this finding is most likely confounded by sun exposure. We found no associations between vitamin D intake skin cancers, except positive associations with BCC risk.