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“Cutaneous melanomas are rare in children and much less common in adolescents than in later life,” researchers led by Mary-Ann El Sharouni, PhD, wrote in the study, which was published online in the Journal of the American Academy of Dermatology. “Management of these young patients currently follows guidelines developed for adults. Better understanding of melanoma occurring in the first 2 decades of life is, therefore, warranted.”
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Drawing from two datasets – one from the Netherlands and the other from Melanoma Institute Australia (MIA) at the University of Sydney – Dr. El Sharouni of the MIA and of the department of dermatology at University Medical Center Utrecht in the Netherlands, and colleagues, evaluated all patients younger than 20 years of age who were diagnosed with invasive melanoma between January 2000 and December 2014. The pooled cohort included 397 Dutch and 117 Australian individuals. Of these, 62 were children and 452 were adolescents. To determine melanoma subtypes, the researchers reevaluated pathology reports and used multivariate Cox models to calculate recurrence-free survival (RFS) and overall survival (OS).
The median Breslow thickness was 2.7 mm in children and 1.0 mm in adolescents. Most patients (83%) had conventional melanoma, which consisted of superficial spreading, nodular, desmoplastic, and acral lentiginous forms, while 78 had spitzoid melanoma and 8 had melanoma associated with a congenital nevus. The 10-year RFS was 91.5% in children and 86.4% in adolescents (P =.32), while the 10-year OS was 100% in children and 92.7% in adolescents (P = .09).
On multivariable analysis, which was possible only for the adolescent cohort because of the small number of children, ulceration status and anatomic site were associated with RFS and OS, whereas age, sex, mitotic index, sentinel node status, and melanoma subtype were not. Breslow thickness > 4 mm was associated with worse RFS. As for affected anatomic site, those with melanomas located on the upper and lower limbs had a better overall RFS and OS compared with those who had head or neck melanomas.
The authors acknowledged certain limitation of the analysis, including its retrospective design and the small number of children. “Our data suggest that adolescent melanomas are often similar to adult-type melanomas, whilst those which occur in young children frequently occur via different molecular mechanisms,” they concluded. “In the future it is likely that further understanding of these molecular mechanisms and ability to classify melanomas based on their molecular characteristics will assist in further refining prognostic estimates and possible guiding treatment for young patients with melanoma.”
Rebecca M. Thiede, MD, assistant program director of the division of dermatology at the University of Arizona, Tucson, who was asked to comment on the study, said that the analysis “greatly contributes to dermatology, as we are still learning the differences between melanoma in children and adolescents versus adults.
This study found that adolescents with melanoma had worse survival if mitosis were present and/or located on head/neck, which could aid in aggressiveness of treatment.”
Dr. Rebecca M. Thiede
A key strength of analysis, she continued, is the large sample size of 514 patients, “given that melanoma in this population is very rare. A limitation which [the researchers] brought up is the discrepancy of diagnosis via histopathology of melanoma in children versus adults. The study relied on the pathology report given the retrospective nature of this [analysis, and it] was based on Australian and Dutch populations, which may limit its scope in other countries.”
Dr. El Sharouni was supported by a research fellowship grant from the European Academy of Dermatology and Venereology (EADV), while two of her coauthors, Richard A. Scolyer, MD, and John F. Thompson, MD, were recipients of an Australian National Health and Medical Research Council Program Grant. The study was also supported by a research program grant from Cancer Institute New South Wales. Dr. Thiede reported having no financial disclosures.