NCI Childhood Cancer Data Initiative (CCDI) Led Pediatric, Adolescent, and Young Adult Rare Cancer Registry for Very Rare Solid Tumors

Background: * Rare cancers are defined by the NCI as fewer than 15 incident cases per 100,000 people per year. Overall, pediatric tumors account for less than 1% of all cancers diagnosed in the United States (US) per year. * The European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) group has determined that the definition of very rare pediatric cancers is fewer than 2 cases per million per year and/or those not eligible for clinical trials. * Frequently, for these very rare solid tumors and hematologic malignancies, little is known about their natural history, including clinical behavior, molecular/genetic characteristics, optimal management, drug response, and evidence-based standard therapy does not exist. Many patients endure the challenges of achieving an accurate and timely diagnosis, along with the difficulty of identifying a center with treatment expertise. * Although several disease-specific pediatric and adult rare cancer efforts exist, they are frequently siloed without standardization across efforts; and, many rare cancers have not been systematically studied. Objective: -To establish a longitudinal observational study and registry for very rare pediatric and Adolescents and Young Adults (AYA) solid tumors Eligibility: -Pediatric, adolescent, or young adult participants (\<= 39 years old at diagnosis) with very rare solid tumors Design: * This will be a longitudinal observational study and registry for children and AYAs with very rare cancers. * Recruitment will be through 2 mechanisms, the Children s Oncology Group s (COG) Project EveryChild Protocol (APEC14B1, NCT02402244) and physician/self-referral. * This study will be led by the NCI s CCDI and NCI s POB. * Enrollment, including consent, distribution of family history/individual medical history/patient report outcome questionnaires, collection of medical records and tissue/saliva/buccal samples, and extraction of data, as well as longitudinal follow-up will be managed centrally. * Tumor tissue and saliva/buccal samples will be run through the CCDI s Molecular Characterization Initiative (MCI) for comprehensive clinical molecular profiling. The remaining samples will be banked for research analyses. Research analysis will be per the CCDI research characterization pipeline. * Since long-term follow-up of individuals with very rare cancers is a major feature of the study, we intend to maintain active contact with study participants for up to 5 years. * Data will be deposited into the CCDI Data Ecosystem.