Men may have a higher incidence of melanoma on the trunk, whereas women may show higher rates on the lower limbs, with these patterns varying by age and population, according to a new study.
In the study, published in the Journal of Investigative Dermatology, investigators analyzed melanoma incidence trends from 1982 to 2018 in Queensland, Australia, the U.S. White population, and Scotland, focusing on sex-specific differences in melanoma by anatomic site. Using age-period-cohort models, the investigators examined variations in melanoma rates by age group, sex, and body site, aiming to assess whether sex-based differences have persisted over time.
The average annual percent change (AAPC) in melanoma incidence from 1982 to 2018 showed an increase in men and women. Compared with women, men had an AAPC of 1.8% vs 1.3% in Queensland, 2.9% vs 2.5% in the U.S. White population, and 3.9% vs 2.4% in Scotland.
From 1982 to 2018, the average annual percent change (AAPC) in melanoma incidence varied by anatomic site. For melanoma on the trunk, men in Queensland saw a 2.1% AAPC and women a 2.2% AAPC, whereas in the U.S. White population, men experienced a 2.5% AAPC and women a 2.8% AAPC. In Scotland, men had a 4.4% AAPC and women a 4.6% AAPC. For the lower limbs, the AAPC in Queensland was 1.9% for men and 1.1% for women. In the U.S. White population, men had a 2.8% AAPC and women a 1.8% AAPC. In Scotland, men saw a 1.9% AAPC and women a 1.3% AAPC.
The findings demonstrated that men exhibited higher rates of melanoma on the trunk, head, and neck, with these rates increasing with age. By contrast, women had higher melanoma incidence on the lower and upper limbs, particularly prior to age 65. However, an increase in truncal melanomas among women was observed in recent years across all populations. One possible reason for the observed patterns of melanoma by body site, as well as recent shifts in these trends, is that men and women tend to have different exposure levels to sunlight and artificial UV sources, and these exposure patterns have evolved over the past several decades. The investigators noted it may be possible that the differences in melanoma distribution between men and women across these populations could be influenced by factors beyond clothing choices or UV exposure patterns. Biological factors related to melanocytic cell growth may also contribute, as studies consistently show that the distribution of nevi varies between boys and girls in ways that reflect the melanoma patterns seen in adults. Data indicated a higher incidence of melanoma in men on the trunk and head/neck beginning around age 25, whereas women showed higher rates on the lower limb, with this trend persisting into older age groups.
In 2018, women had the highest melanoma incidence on the lower and upper limbs. In the U.S. White population, rates were 7.48 per 100,000 individuals for the lower limbs and 7.49 per 100,000 individuals for the upper limbs. In Scotland, the incidence was 7.54 per 100,000 individuals for the lower limbs and 5.49 per 100,000 individuals for the upper limbs. In Queensland, rates were 20.86 per 100,000 individuals for the upper limbs and 15.77 per 100,000 individuals for the lower limbs.
In all populations studied, men had the highest rates of melanoma on the trunk. In 2018, the incidence was 35.86 per 100,000 individuals in Queensland, 14.67 per 100,000 individuals in the U.S. White population, and 8.45 per 100,000 individuals in Scotland.
The male-to-female incidence rate ratio revealed that by age 80, men had a melanoma rate on the trunk that was four times higher than women across all populations. For the head and neck, men had a higher incidence at all ages in the United States, starting after age 30 in Queensland, and after age 50 in Scotland. Conversely, women had higher melanoma rates on the lower limbs across most age groups.
The study, also identified “turning points” in melanoma incidence based on birth cohorts, with patterns differing by population and anatomic site, suggesting that changes in UV exposure may have influenced these trends. These findings indicated potential differences in sex-specific susceptibility to melanoma, possibly linked to environmental factors such as UV radiation and intrinsic biological variations between the sexes.
The authors reported no conflicts of interest.
