Second Malignancies in Children and Adolescents With Extracranial Germ Cell Tumors: A Report From the Malignant Germ Cell Tumor International Consortium.

Whilst men with testicular cancer have a twofold increase in second malignant neoplasms (SMNs), the risk in children with germ cell tumors (GCTs) is not fully quantified. SMNs in children treated for GCTs was assessed in the Malignant Germ Cell Tumor International Consortium data commons (n = 917). Thirteen SMNs were identified with median follow-up of only 5.9 years. Assigning cause is nuanced because GCT-related SMNs can either be treatment related, second primary malignancies from a common primordial germ cell progenitor, or somatic malignant transformation of the original GCT. Longer follow-up of children with GCT is needed to ascertain risk and understand causation.