Indoor tanning and the risk of developing non-cutaneous cancers: a systematic review and meta-analysis
Despite a strong association between indoor tanning and the risk of cutaneous cancers, the relationship between indoor tanning and non-cutaneous cancers is unknown. Our objective was to estimate the association of indoor tanning with developing non-cutaneous cancers.
We conducted a systematic literature review and meta-analysis of the association between indoor tanning and non-cutaneous cancer sites. Associations were estimated using random effects models. Heterogeneity was investigated through subgroup analyses and the Q-test and I2 statistics.
From 15 identified studies, 33 effect estimates for 12 cancer sites were included in the review. Adjustment for sun exposure was a significant source of heterogeneity in the association of indoor tanning and non-cutaneous cancer risk (meta-regression p = 0.0043). When restricting to studies that adjusted for solar ultraviolet radiation (7 studies and 19 effect estimates) a potential increased risk was observed among ever users of indoor tanning devices with the risk of hematologic malignancies (pooled relative risk = 1.11; 95% CI 0.96–1.28), with differing effects observed by hematologic types and subtypes of non-Hodgkin lymphoma. No association was observed among solid non-cutaneous cancers (pooled relative risk = 0.98; 95% CI 0.94–1.19). Neither study design nor geographical region was significant sources of heterogeneity in these associations.
When controlling for sun exposure, indoor tanning does not protect against solid non-cutaneous cancers and may increase the risk of some hematologic malignancies. Given the well-established relationship with skin cancer and potential relationship with hematologic malignancies, efforts to reduce the use of indoor tanning devices should continue.
KeywordsIndoor tanning Cancer Hematologic malignancies Review Etiology
Preferred Reporting Items for Systematic Reviews and Meta-Analyses
Dylan O’Sullivan is supported by a Queen Elizabeth II Scholarship and an Empire Life Fellowship. Troy Hillier is supported by an Empire Life Fellowship. Darren Brenner holds a Canadian Cancer Society Cancer Prevention Capacity Development Award (#703917).
Compliance with ethical standards
Conflict of interest
No conflicts of interest exist.
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