Treating rare cancer in children: the importance of evidence

The study of pediatric rare cancers, which account for approximately 9% of all childhood malignancies, has been hindered by their histologic heterogeneity and by their preferential occurrence in adolescents, a population that has been underrepresented in clinical trials sponsored by the National Cancer Institute. The use of cooperative group and investigator-initiated registries can help improve our ability to identify and select populations of patients with rare cancers that can benefit from single-arm studies, and incorporation of biologic aims and tissue banking can accelerate our understanding of the biology of these cancers. These studies should be promoted further through expansion of international outreach efforts. Well-designed preclinical models that accurately recapitulate human disease offer an attractive alternative to the study of rare cancers and may accelerate the process of target identification and drug discovery and development. The concept of specialized clinics for selected rare cancers has proven to be very successful in pediatric gastrointestinal tumors. This paradigm should be further explored in other rare cancers because it offers an unprecedented opportunity to collaborate closely with interested investigators. In addition, it offers patients an opportunity to discuss their disease with specialists, allows these patients to provide tissue for further research, and ultimately can promote the development of clinical trials that are unique for that specific disease.