title: Sex differences in numbers of nevi on body sites of young European children: implications for the etiology of cutaneous melanoma.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Unit of Epidemiology and Prevention, Jules Bordet Institute, 125 Boulevard of Waterloo, Brussels 1000. philippe.autier@bordet.be
authors.forename: Philippe
authors.initials: P
authors.lastname: Autier
authors.forename: Mathieu
authors.initials: M
authors.lastname: Boniol
authors.forename: Gianluca
authors.initials: G
authors.lastname: Severi
authors.forename: Remy
authors.initials: R
authors.lastname: Pedeux
authors.forename: André-Robert
authors.initials: AR
authors.lastname: Grivegnée
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Doré
mesh_terms: D002648:Child; D003020:Clothing; D003430:Cross-Sectional Studies; D004781:Environmental Exposure; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D009506:Nevus / Q000453:epidemiology / Q000473:pathology*; D012737:Sex Factors; D012878:Skin Neoplasms / Q000453:epidemiology / Q000473:pathology*; D013472:Sunlight