RARE CHILDOOD CANCER

Rare cancers: a sea of opportunity

Niki Boyd, PhD

Prof Janet E Dancey

Prof C Blake Gilks, MD

Prof David G Huntsman, MD

Volume 17, No. 2, e52–e61, February 2016

Summary

Rare cancers, as a collective, account for around a quarter of all cancer diagnoses and deaths. Historically, they have been divided into two groups: cancers defined by their unusual histogenesis (cell of origin or differentiation state)—including chordomas or adult granulosa cell tumours—and histologically defined subtypes of common cancers. Most tumour types in the first group are still clinically and biologically relevant, and have been disproportionately important as sources of insight into cancer biology. By contrast, most of those in the second group have been shown to have neither defining molecular features nor clinical utility. Omics-based analyses have splintered common cancers into a myriad of molecularly, rather than histologically, defined subsets of common cancers, many of which have immediate clinical relevance. Now, almost all rare cancers are either histomolecular entities, which often have pathognomonic mutations, or molecularly defined subsets of more common cancers. The presence of specific genetic variants provides rationale for the testing of targeted drugs in rare cancers. However, in addition to molecular alterations, it is crucial to consider the contributions of both mutation and cell context in the development, biology, and behaviour of these cancers. Patients with rare cancers are disadvantaged because of the challenge of leading clinical trials in this setting due to poor accrual. However, the number of patients with rare cancers will only increase as more molecular subsets of common cancers are identified, necessitating a shift in the focus of clinical trials and research into these cancer types, which, by epidemiological definitions, will become rare tumours.

The burden of rare cancers in Europe.

Gatta G, Capocaccia R, Trama A, Martínez-García C; RARECARE Working Group.

Collaborators (149)

Abstract

The burden of rare tumors in Europe is still unknown and no generally accepted definition of them exist. The Surveillance of Rare Cancers in Europe project (funded by the European Commission) aimed at providing a definition of "rare cancer", a list of cancers and rare cancer burden indicators, based on population-based cancer registry data, across Europe. An international consensus group agreed that incidence is the most appropriate indicator for measuring rare cancers frequency and set the threshold for rarity at 6/100,000/year. The list of rare cancers was based on the International Classification of Diseases for Oncology (ICD-O 3rd edition) and it was hierarchically structured in 2 layers based on various combinations of ICD-O morphology and topography codes: layer (1) families of tumors (relevant for the health care organisation) and layer (2) tumors clinically meaningful (relevant for clinical decision making and research). The burden indicators were estimated and are provided in this chapter.