Cases of melanoma among U.S. adolescents and young adults declined markedly from 2006 to 2015 - even as the skin cancer's incidence continued to increase among older adults and the general population during the span, new research shows.

The finding, based on national cancer-registry data, suggests that public-health efforts advocating sun protection are changing behaviours among Millennials and Post-Millennials, the investigators surmised.

JAMA Dermatology published the study, which was conducted by clinicians and researchers at the University of Washington School of Medicine and Fred Hutchinson Cancer Research Center in Seattle.

"There seems to be a breakthrough happening that might really reverse the trend for increasing melanoma incidence," said Margaret Madeleine, a co-senior author of the study and a Fred Hutchinson epidemiologist specialising in cancer-incidence trends.

Melanoma, triggered by ultraviolet radiation from the sun, is the most common skin cancer and is fifth most common among all cancers in U.S. men and women.

If it is detected and treated early, patients have a better than 95% chance of surviving five years or more.

If not caught early, though, it can spread to structures such as the lungs, brain, or liver, and become highly lethal.

"The vast majority of my practice is older and middle-age adults, but absolutely melanoma can affect younger patients," said Dr. Jennifer Gardner, co-senior editor of the study and a clinical assistant professor of medicine (dermatology) at the UW School of Medicine.

"I do have patients who are in the prime of their life and otherwise healthy, and they're thinking about other things and bigger ambitions, and unfortunately this diagnosis really hits them quite hard."

The researchers gathered de-identified patient data of 988,000 invasive melanoma cases from databases at the Centers for Disease Control and Prevention and the National Cancer Institute. In analysing data, the investigators calculated annual percentage of change for multiple demographics, including age: paediatric (ages 0-9), adolescent (10-19), young adult (20-29), and adults in 10-year increments from 30 to 80 .

"We were wondering, with the advent of public health programs to increase sun protection - sunscreen and hats and staying in the shade and all the recommendations for skin cancer prevention - if that effort is working. Is there a corresponding decrease we can see reflected in melanoma rates?" said Madeleine.

The researchers found that, across all ages, the number of melanoma cases rose steadily during the study span, from 50,272 in 2001 to 83,362 in 2015.

The overall increasing incidence rates seen over time was primarily driven by adults 40 years, the authors wrote.

However, for adolescents and young adults, incidence peaked around 2005 and then fell sharply through 2015: Among males, the incidence rate dropped about 4% per year and, among females, about 4.5% per year across the two age groups.

The drop-off mirrors reductions in melanoma rates seen among younger populations in Australia starting around 1988, the authors wrote.

They attributed that nation's turnaround to public-health campaigns for sun-protective behaviours, including a "Slip! Slop! Slap!" campaign.

In the United States, Gardner said, "we're doing a better job of treating more advanced types of melanoma, but we are still seeing it increasing overall, so the (public health) work is not done. More efforts for prevention make a lot of sense."

Source: UW Health Sciences Library