Introducing the PLOS collection on rare cancer.

Rare cancers are defined by low incidence rates, and may lack evidence that supports uniform standards of care and relevant clinical guidelines. Rare cancers may represent up to 24% of all cancers, yet remain understudied and underappreciated in terms of their clinical and ultimately societal impact. The PLOS Rare Cancer Collection brings together a broad range of research endeavors that are being undertaken in rare cancers research ranging from basic biological evaluations to therapeutic drug development. This Overview presents a brief background to the Collection and highlights the contributions of included articles.