Familial aggregation of melanoma risks in a large population-based sample of melanoma cases.
OBJECTIVE
Melanoma has been shown in numerous studies to be associated with sun exposure, and with host phenotypic factors of genetic origin. In this study we use information from a large series of incident cases of melanoma from an international population-based study to examine the patterns of incidence of melanoma in the first-degree relatives of these cases.


METHODS
A total of 2508 incident cases of melanoma provided information on basic demographic data and pigmentary characteristics, in addition to detailed information on family history of melanoma. These data were used to examine the incidence rates ratios of melanoma in the relatives of cases in relation to population rates, and also with respect to phenotypic characteristics of the probands that have been shown to be associated with melanoma: mole counts, hair color, eye color, and skin sensitivity to the sun.


RESULTS
The incidence rates reflect the underlying patterns of incidence in the source populations, with generally higher rates in the Australian sample, low rates in Italy, and intermediate rates in the USA and Canada. Also, rates are higher in men than in women, except at very young ages. Phenotypic characteristics of the probands were only weakly associated with the observed rates in the relatives although there is a strong inverse association with age at diagnosis. Cumulative risk of melanoma rises to 6.9% (6.1%) at age 80 in male (female) first-degree relatives of cases, and to 10.8% (9.5%) in relatives of cases diagnosed before age 50.


CONCLUSIONS
Relatives of cases diagnosed with melanoma are at considerable lifetime risk of the disease, especially if the case is diagnosed at a young age.
Begg
Colin B
CB
Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA. korvae@mskcc.org
Hummer
Amanda
A
Mujumdar
Urvi
U
Armstrong
Bruce K
BK
Kricker
Anne
A
Marrett
Loraine D
LD
Millikan
Robert C
RC
Gruber
Stephen B
SB
Anton-Culver
Hoda
H
Klotz
Judith B
JB
Zanetti
Roberto
R
Gallagher
Richard P
RP
Dwyer
Terence
T
Rebbeck
Timothy R
TR
Berwick
Marrianne
M
D000328:Adult; D000367:Age Factors; D000368:Aged; D001315:Australia / Q000453:epidemiology; D015331:Cohort Studies; D005192:Family Health; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology / Q000235:genetics; D006801:Humans; D015994:Incidence; D008297:Male; D008545:Melanoma / Q000453:epidemiology* / Q000235:genetics; D008875:Middle Aged; D009656:North America / Q000453:epidemiology; D010641:Phenotype; D017678:Sex Distribution