Melanoma in the young: Differences and similarities with adult melanoma - A case-matched controlled analysis

Background. Melanoma in the first 2 decades of life is rare and is less well characterized than melanoma in adults. Previously published comparisons of melanoma of the young (age <= 20 years) and in adults have been biased by the observation that primary melanomas of the young are significantly thicker on average than adult melanomas. In this study, the use of an adult control group that was matched for tumor thickness adjusted for this bias and allowed for a comparison of the biology of pediatric melanoma and adult melanoma. Methods. The authors identified young patients with melanoma who were treated at their institution between 1971 and 2002, and matched each patient by thickness and year of diagnosis to 2 adult control patients with melanoma. The study group of 73 young patients with melanoma (aged <= 20 years) was compared with to 146 adult case-matched control patients for clinical presentation, treatment, and clinically relevant outcome parameters, including disease-free and cause-specific survival. A subset of pediatric patients aged <= 13 years also was analyzed against case-matched adult controls. Results. The demographics and clinical presentation of the 2 groups were similar. Of the young patients with melanoma who underwent pathologic staging of clinically negative lymph nodes by either elective lymph node dissection or lymphatic mapping/ sentinel lymph node biopsy, 11 of 25 patients (44%) had positive lymph nodes compared with 11 of 46 patients (23.9%) among the adults. The overall incidence of positive lymph nodes was 17.8% in young melanoma patients and 9.6% in thickness- matched adult control patients. Nonetheless, 10-year cause-specific survival was similar between young melanoma patients and adult melanoma patients (89.4% and 79.3%, respectively). No significant differences were observed comparing young patients with melanoma aged < 13 years versus age > 13 years. Conclusions. Melanoma of the young had some important differences and similarities relative to adult melanoma. Lymph node metastases were more prevalent in young patients with melanoma compared with adult (thickness-matched) control patients; however, the 5- and 10-year survival rates were similar.