Melanoma incidence and mortality may eventually decrease among the entire Swedish population

By Dr. Priyom Bose, Ph.D.Reviewed by Benedette Cuffari, M.Sc.Sep 13 2024

Study finds significant drop in incidence and mortality among 30 to 49-year-olds

Study: Melanoma Incidence and Mortality Trends in Sweden. Image Credit: Inside Creative House / Shutterstock.com

A recent JAMA Dermatology study assesses the incidence of melanoma and mortality trends among younger patients.

The global incidence of melanoma

A steady and well-documented rise in the incidence of melanoma has been documented since the 1960s throughout Europe, North America, and Oceania. This increase is most prominent among older individuals; however, rising rates among prepubertal children, adolescents, and young adults have also been reported.

Over the past several years, the prevalence of melanoma in younger age groups has declined in both Australia and the United States. Incidence stabilization in younger age groups has also been reported in the United Kingdom, Spain, Norway, Canada, and New Zealand; however, a significant decline in melanoma cases has not been observed in any European nation.

At the population level, mortality rates from melanoma have increased in many countries, albeit at a substantially slower rate than the incidence of melanoma. Among younger individuals, a reduction in melanoma mortality rates has been observed.

In Sweden, the median age of invasive melanoma diagnosis is 65 years as compared to 60 years in 1990. Over the past decade, a 6% increase in the incidence of melanoma has been reported each year in Sweden, thereby causing this nation to rank sixth highest in the world for melanoma cases.

About the study

The researchers of the current study assessed the trends in melanoma cases among patients diagnosed at younger than the average age using data obtained from Swedish national health and population registers. Individuals younger than 60 years on the date of surgical treatment for primary invasive cutaneous melanoma in 1990 and 2022 were considered.

Separate analyses were performed by age, sex, and Breslow thickness of the melanoma. Individuals 60 years and older were included for reference in the mortality analyses, whereas all other age groups were split in 10-year windows.

Calculated yearly incidence and mortality rates for every 100,000 inhabitants were performed and reported as average annual rates for each five-year period between 1990 and 2022. Joinpoint regression models were estimated to evaluate the statistical significance of temporal trends and points of change.

Study findings

A total of 34,800 primary invasive cutaneous melanomas were reported in individuals younger than 60, 56.3% of which occurred in female patients. Few melanomas were diagnosed in the youngest age groups, and the incidence of melanoma rose significantly with each additional decade in age.

In children between 13 and 19 years of age, 257 melanomas were diagnosed, whereas 18 cases of melanoma were diagnosed in children between zero and 12 years of age. Among patients between 13 and 49 years of age, females were overrepresented.

Melanoma lesions were more likely to be thinner in both sexes who were between 20 and 49 years of age as compared to the 50-59 and 0-19 years groups. Until 2013 and 2015, a significant increase in melanoma tumors thicker than one millimeter (mm) was observed in male and female 40- to 49-year-old patients, respectively. Thereafter, a significant reduction in tumor thickness was observed for both females and males.

In the 50-59 age group, a persistent increase in the incidence of melanoma was observed for females and males. In the other age groups, except those younger than 20 years of age, an incidence peak from 2013 to 2015 was observed, which was subsequently followed by a significant and stable decline until 2022.

No notable incidence trends were observed in individuals younger than 20 years of age. Although males between zero and 19 years of age were not associated with a significant change in the incidence of melanoma, females in this age group exhibited a significant decline.

A significant rise was observed in melanoma-related mortality in individuals 60 years of age and older, particularly males. Comparatively, among individuals between 30 and 59 years of age, a significant decrease in melanoma mortality was observed.

No significant joinpoints or changes over time were reported in patients up to 29 years of age, with this age group associated with an annual melanoma rate of less than 0.1 per 100,000 people.

Conclusions

In Sweden, adults between 30 and 49 years of age experienced a significant reduction in their likelihood of being diagnosed and/or dying from melanoma. Although future research is needed to elucidate the exact mechanisms responsible for this decline, public health campaigns, ultraviolet (UV) protection, and changing population demographics may be, in part, responsible.