Sex differences in numbers of nevi on body sites of young European children: implications for the etiology of cutaneous melanoma.
ABSTRACT Since 1950, the greatest increase in cutaneous melanoma incidence in fair-skinned males took place on the trunk and on the head and neck, whereas in females, it took place on the limbs, mainly on the lower limbs. We examined the influence of sex on numbers and size of nevi on different body sites in white European schoolchildren.
Information about each holiday period since birth to interview was recorded from parents of six hundred twenty-eight 6- to 7-year-old children in four European cities (Brussels (Belgium), Bochum (Germany), Lyons (France), and Rome (Italy)). Number and anatomic location of small (2-4.9 mm) and large (>/=5 mm) nevi and individual susceptibility to sunlight were independently assessed.
After adjustment for host characteristics, sun exposure, and sun protection habits, males had 7% [95% confidence interval (95% CI), -7 to 19] more small nevi than females. However, compared to females, numbers of small nevi were increased by 17% (95% CI, 1-31) on the head and neck and by 16% (95% CI, 2-27) on the trunk and shoulders. In contrast, in males, the number of small nevi on upper limbs was decreased by -5% (95% CI, -26 to 13), and on lower limbs by -8% (95% CI, -34 to 13). The number of large nevi was 6% higher in males than in females (95% CI, -26 to 30).
The sex differences in small nevus distribution in schoolchildren reflect the sex differences in the anatomic distribution of melanoma in adults. Sex differences in sun exposure behaviors, dressing, and clothing would just add their effects to the sex-dependent inherited propensity to develop nevi on a given body site. These results reinforce the hypothesis by which childhood would be a decisive period for the occurrence of sun-induced biological events implicated in the genesis of cutaneous melanoma.
- SourceAvailable from: Jadranka Bozikov
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- "Mathematically, a single mutation can be at the base of the formation of melanocytic nevi, with a probability of mutation per cell per mitosis between 10 -9 and 10 -7 . The number and size of nevi during lifetime is not definitely and with certainty established, but roughly their number increase during the two first decades, reaching the maximum during the second and third decade, and after that their number diminishes          . "
ABSTRACT: Melanocytic nevi (moles) are common, and can be found anywhere on the skin. Their number has been shown to be associated with a greater risk of cutaneous melanoma. Also, the knowledge of their natural evolution is important in the understanding of the development of melanoma. The aim of this study was to incorporate available knowledge about melanocytic proliferation and the role of immune system and to create a simulation model which will be able to explain the changes in number of melanocytic nevi during lifetime and to elucidate the importance of the immune system in their formation and regression (i.e. eruptive benign melanocytic nevi). The results were presented graphically and visually analyzed. Because of the great number of possible numerical solutions only approximately results that satisfy some basic criteria were take into account. A created system dynamics model proved to be able to simulate the appearance and disappearance of melanocytic nevi during lifetime and the eruption of nevi after immunosuppression in a way that mimics their changes reported in epidemiological studies. There are limitations in model assumptions due to many uncertainties regarding model parameters and thus much more detailed epidemiological data would be required for the creation of a more reliable model. Jadranka Božikov graduated in Mathematics and earned MSc and PhD degree in field of Biomedicine and Health Sciences at Zagreb University. Since 1978 she works in Department for Medical Statistics, Epidemiology and Medical Informatics at Andrija Štampar School of Public Health, Medical School, University of Zagreb, currently as associated professor. She introduced simulation modeling methods and applications as teaching subject for medical students and graduates and supervised several MSc theses obtained by young researchers who employed system dynamics approach and continuous simulation techniques in their investigation of the phenomena in medicine and public health. URL: www.snz.hr/~jbozikov.