, according to results of a population-based registry study of 988,103 cases of invasive melanoma.
These data are observational, “and thus cannot conclusively determine the cause of this statistically and clinically significant decrease,” wrote Kelly G. Paulson, MD, PhD, of the Fred Hutchinson Cancer Research Center, Seattle, and colleagues. However, they added, “a likely explanation for the reduced melanoma incidence in adolescents and young adults is success at increased UV exposure protection. These data provide an impetus to further improve multimodal efforts aimed at reducing the burden of melanoma and encourage ongoing UV exposure protection efforts throughout the lifetime of individuals.”
Public health measures to promote sun-protective behaviors including sunscreen use, protective clothing, and seeking shade were initiated in the United States in the late 1990s and early 2000s, but the public health impact remains unknown, they noted in the study, published in JAMA Dermatology.
For the study, they reviewed data from the National Program of Cancer Registries – Surveillance Epidemiology and End Results combined database for the years 2001-2015. Overall, the incidence of invasive melanoma among people of all ages in the United States increased from 50,272 cases in 2001 to 83,362 in 2015. However, in 2015 only 67 cases were reported in children younger than 10 years, 251 in adolescents aged 10-19 years, and 1,973 in young adults (aged 20-29 years).
Between 2006 and 2015, the annual percentage change in melanoma incidence decreased by 4.4% for male adolescents, 5.4% for female adolescents, 3.7% for male young adults, and 3.6% for female young adults; these changes were statistically significant. The trends in incidence was similar when the population was limited to non-Hispanic whites, considered a high-risk group for melanoma.
By contrast, melanoma incidence increased by an annual percentage change of 1.8% for both men and women aged 40 years and older during the same period of time. Young adult women had a greater incidence of melanoma compared with young adult men (about twofold greater), but older men had a greater incidence of melanoma compared with older women, the researchers said.
The findings were limited by a lack of data about potential confounders, such as skin pigmentation, UV light exposure, sunburn history, sunscreen use, sun avoidance, protective clothing, and tanning bed use; and the absence of information kept the researchers from estimating an association between increased sun-protective behaviors and decreased incidence of melanoma.
“However, this change in behavior remains a plausible explanation for decreased melanoma rates in adolescent and young adult populations,” and the data support continued strategies to promote UV protection throughout life, they said.
The study was supported in part by the National Institutes of Health, the Fred Hutchinson Cancer Research Center Integrated Immunotherapy Research Core, and a Society for Immunotherapy of Cancer–Merck fellowship. Dr. Paulson disclosed grants from the Society for Immunotherapy of Cancer–Merck, bluebird biosciences, EMD Serono; she also disclosed an issued and licensed patent for a Merkel cell carcinoma T cell receptor.
SOURCE: Paulson KG et al. JAMA Dermatol. 2019. Nov 13. doi: 10.1001/jamadermatol.2019.3353.