title: Melanoma in adolescents: a case-control study of risk factors in Queensland, Australia.
abstract: The incidence of melanoma increases markedly in the second decade of life but almost nothing is known of the causes of melanoma in this age group. We report on the first population-based case-control study of risk factors for melanoma in adolescents (15-19 years). Data were collected through personal interviews with cases, controls and parents. A single examiner conducted full-body nevus counts and blood samples were collected from cases for analysis of the CDKN2A melanoma predisposition gene. A total of 201 (80%) of the 250 adolescents with melanoma diagnosed between 1987 and 1994 and registered with the Queensland Cancer Registry and 205 (79%) of 258 age-, gender- and location-matched controls who were contacted agreed to participate. The strongest risk factor associated with melanoma in adolescents in a multivariate model was the presence of more than 100 nevi 2 mm or more in diameter (odds ratio [OR] = 46.5, 95% confidence interval [CI] = 11.4-190.8). Other risk factors were red hair (OR = 5.4, 95%CI = 1.0-28.4); blue eyes (OR = 4.5, 95%CI = 1.5-13.6); inability to tan after prolonged sun exposure (OR = 4.7, 95%CI = 0.9-24.6); heavy facial freckling (OR = 3.2, 95% CI = 0.9-12.3); and family history of melanoma (OR = 4.0, 95%CI = 0.8-18.9). Only 2 of 147 cases tested had germline variants or mutations in CDKN2A. There was no association with sunscreen use overall, however, never/rare use of sunscreen at home under the age of 5 years was associated with increased risk (OR = 2.2, 95%CI = 0.7-7.1). There was no difference between cases and controls in cumulative sun exposure in this high-exposure environment. Factors indicating genetic susceptibility to melanoma, in particular, the propensity to develop nevi and freckles, red hair, blue eyes, inability to tan and a family history of the disease are the primary determinants of melanoma among adolescents in this high solar radiation environment. Lack of association with reported sun exposure is consistent with the high genetic susceptibility in this group.
authors.affiliation: Queensland Cancer Fund, Brisbane, Australia.
authors.forename: Philippa
authors.initials: P
authors.lastname: Youl
authors.forename: Joanne
authors.initials: J
authors.lastname: Aitken
authors.forename: Nicholas
authors.initials: N
authors.lastname: Hayward
authors.forename: David
authors.initials: D
authors.lastname: Hogg
authors.forename: Ling
authors.initials: L
authors.lastname: Liu
authors.forename: Norman
authors.initials: N
authors.lastname: Lassam
authors.forename: Nicholas
authors.initials: N
authors.lastname: Martin
authors.forename: Adèle
authors.initials: A
authors.lastname: Green
mesh_terms: D000293:Adolescent; D001315:Australia / Q000453:epidemiology; D016022:Case-Control Studies; D005260:Female; D019942:Genes, p16; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008545:Melanoma / Q000453:epidemiology* / Q000209:etiology / Q000235:genetics; D015999:Multivariate Analysis; D009154:Mutation; D012307:Risk Factors; D013472:Sunlight / Q000009:adverse effects