title: Similar anatomical distributions of childhood naevi and cutaneous melanoma in young adults residing in northern and southern Sweden.
abstract: BACKGROUND
  Common melanocytic naevi are considered early biomarkers associated with risk of cutaneous malignant melanoma. We sought to investigate if residing at different latitudes in Sweden influences the population's anatomical distribution of naevi in children and melanoma in adults.
  
  
  METHODS
  The nationwide Swedish Cancer Registry 1990-2012 gave cumulative number of invasive melanomas per body site, stratified by sex and age in northern (62-69 °N) (n=2823) and southern (55-58 °N) Sweden (n=24,115). A population-based cross-sectional study conducted in 2002 provided the allocation of naevi among 7-year-olds in northern (5695 naevi in 679 children) and southern Sweden (8392 naevi in 681 children).
  
  
  RESULTS
  In 2012, northern Sweden had a two-fold lower melanoma incidence: 19.8/100.000 age-standardised population compared with 41.0/100.000 in the south. Similarly, a lower mean naevi density in children was demonstrated: 7.3 (standard deviation (SD) 5.4) in boys and 7.0 (4.7) in girls in the north versus 13.3 (8.4) in boys and 11.9 (8.5) in girls in the south. Across latitudes of residing, gender profiles and proportional body-site distributions of melanoma and naevi, respectively, were largely homogenous, but in southern Sweden slightly higher on the trunk; a body site associated with intermittent sun exposure. Childhood naevi distributions matched with melanomas in young and middle-aged adults.
  
  
  CONCLUSIONS
  This large population-based study demonstrated that latitude of residing similarly affects the number and anatomical distribution of naevi in children and melanoma in adults. It supports a role of childhood naevi as predictors of overall and subsite risk of melanoma among young adults.
authors.affiliation: Dermatology and Venereology Unit, Department of Medicine Solna, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden. Electronic address: maria.karlsson@karolinska.se.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Karlsson
authors.affiliation: Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Ylva
authors.initials: Y
authors.lastname: Rodvall
authors.affiliation: Dermatology and Venereology Unit, Department of Medicine Solna, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Carl-Fredrik
authors.initials: CF
authors.lastname: Wahlgren
authors.affiliation: Karolinska Institutet, Stockholm, Sweden.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Wiklund
authors.affiliation: Dermatology and Venereology Unit, Department of Medicine Solna, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Bernt
authors.initials: B
authors.lastname: Lindelöf
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D000368:Aged; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008545:Melanoma / Q000453:epidemiology / Q000473:pathology*; D008875:Middle Aged; D009506:Nevus / Q000453:epidemiology / Q000473:pathology*; D012042:Registries; D012111:Residence Characteristics; D012307:Risk Factors; D017678:Sex Distribution; D012737:Sex Factors; D012878:Skin Neoplasms / Q000453:epidemiology / Q000473:pathology*; D013472:Sunlight / Q000009:adverse effects; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects; D055815:Young Adult
keywords: Children; Epidemiology; Geographic location; Melanocytic nevus; Melanoma; Ultraviolet radiation