Objectives Melanoma of the skin has been rapidly increasing in the United States: in 2015, the incidence of melanoma (invasive and in-situ) was nearly 6-times that reported in 1975. The predominant explanation for this increased incidence has been increased exposure to UV radiation.

Method Using data from meta analyses quantifying the relative risk of melanoma associated with various types of UV exposure, we explored whether or not the association could explain the observed melanoma trends. We find that the strongest UV associated risk factor, frequent sunburns, was associated with a relative risk of 2.03 [95% CI, 1.73–2.37]. We modeled the expected incidence trend under the extreme condition that there was no population exposure to sunburn prior to 1975 and that the entire population was exposed in 2015.

Results Even under this extreme condition of a population wide exposure that doubles risk of melanoma, it is not possible to explain the observed 6-fold increase in melanoma as a consequence of UV exposure.

Conclusions Our findings suggest that a substantial proportion of the increased incidence melanoma is either the result of an unknown, powerful exposure or an epidemic of diagnosis.