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Melanoma incidence increased among children, adolescents
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Recent data from a review of nine US cancer registries indicate that the incidence of childhood and adolescent melanoma has been increasing in the United States at an average of 2% per year.
“Whereas melanomas in older children and adolescents (≥10 years) behave similarly to adult melanomas, those in younger individuals are thought to have a different etiology,” Jeannette R. Wong, MPH, of the radiation epidemiology branch of the Division of Cancer Epidemiology and Genetics of the National Cancer Institute, and colleagues wrote. “Unlike adults, more girls are affected than boys, and whites are at a higher risk than other racial groups.”
To assess potential causes underlying the increased number of melanoma cases, Wong and colleagues used data from the Surveillance, Epidemiology and End Results (SEER) database to examine trends in melanoma incidence among 1,230 whites diagnosed between aged 0 and 19 years.
The researchers investigated trends by sex, stage, age at diagnosis and primary site, as well as ultraviolet B (UVB) radiation exposure levels.
Wong and colleagues calculated age-adjusted incidence rates, annual percent changes and 95% CIs for each category of interest. Incidence trends also were assessed using joinpoint and loess regression models. Additionally, SEER registries were categorized with respect to low or high UVB radiation exposure.
Results indicated that females aged 15 to 19 years and those with low UVB exposure exhibited significantly higher incidence rates than males, younger children and those living in SEER registries categorized as high UVB.
“While overall trends were similar for both genders, melanoma incidence in boys is specifically increasing on the skin of the face and trunk, but only on the lower limbs and hip for girls,” Wong and colleagues wrote.
The only decreased incidence trend the researchers observed was among 15- to 19-year-olds in the high UVB exposure group from 1985 from 2009. Loess curves indicated similar patterns.
“Despite increasing rates, we note that malignant melanoma survival rates have increased since the 1970s,” the researchers wrote. “Five-year survival is currently nearly 100% for cases diagnosed in localized stages vs. 82% for cases diagnosed in regional or distant stages. These data emphasize the importance of early detection.”
Perspective
Back to TopJose Lutzky, MD
Risk factors for the development of melanoma in children and adolescents are a subject of major epidemiologic interest. Wong and colleagues reviewed SEER registry data from 1973 to 2009 for melanoma patients aged 0 to 19 years. They identified 1,230 white patients. The objectives were to analyze trends in the incidence of melanoma in this age group by gender, stage, primary site and UVB exposure levels. UVB exposure levels were estimated based on geographic location, altitude and sky cover.
Melanoma incidence was 1.6-fold higher in girls. The incidence of melanoma increased 2% per year overall. Girls, 15- to 19-year-olds, and those who live in low-risk UVB exposure locations were at higher risk of melanoma than boys, younger children and those who live in high-risk UVB exposure locations. Boys had increased incidence of melanoma in the face and trunk, whereas girls were more affected in the lower limbs and hips. An upstaging trend was noted beginning in the early 1990s, possibly related to the increasing use of sentinel lymph node biopsies.
Possible explanations for the overall increase in incidence included increased UVB and UVA exposure, increased diagnoses of thin melanomas and overdiagnosis. The apparently paradoxical higher risk of melanoma in low-risk UVB exposure area may be related to increased exposure to UVA from indoor sources (such as tanning beds) in these areas, particularly in girls. Increased awareness of the risks of UV exposure in more recent years could be a factor in the stable incidence rates in the younger cohorts. The interesting and important observations and hypotheses generated from this study should be further dissected and tested in selected populations in which individualized data can be obtained and analyzed.
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