Rare cancers (those with incidence rates of < 6 per 100 000 people per year) represent a substantial burden of disease. About 5.1 million people in the European Union and the United Kingdom are affected by rare cancers, and more than 650 000 new cases are diagnosed per year. Although individually each of the 198 currently identified rare cancers is considered rare, collectively they account for about 24% of all cancer cases diagnosed each year (Gatta et al., 2011), including rare adult solid tumours (13%), rare haematological cancers (8%), and all childhood cancers (1%) (Gatta et al., 2017). Despite the high collective occurrence of rare cancers, basic biological and clinical knowledge is lacking. Many of the barriers to research stem directly from the low incidence rates of individual tumour types. Although tens of thousands of patients may be living with a given rare cancer, the geographical dispersion of the patients often limits the number of cases seen at any one institution. In basic research settings, a scarcity of rare tumour tissue and patient-derived models can preclude well-powered studies aimed at elucidating the underlying biology (Boehm and Golub, 2015). Patients with rare cancers can be disadvantaged because of the rarity of the disease. Rare cancers are understudied, economies of scale cannot be achieved, the market is not large enough to incentivize drug development, and benefits in outcomes for new therapeutic strategies cannot be demonstrated through conventional studies (https://www.rarecancerseurope.org/). Whereas the situation is challenging for post-diagnostic studies, the pre-diagnostic setting is even worse; etiologies are frequently unknown, and pre-diagnostic biomarkers are almost non-existent. For many patients with a rare cancer, the lack of effective clinical management before and after diagnosis translates into a suboptimal clinical outcome; on average, patients with rare cancers have worse outcomes, with estimated average 5-year relative survival rates of 47% for patients with rare cancers versus 65% for those with common cancers (Gatta et al., 2011).
A list of rare cancers has been provided by the European Union (EU)-funded RARECARE project (http://rarecarenet.istitutotumori.mi.it/rarecarenet/), based on the International Classification of Diseases for Oncology, 3rd edition (ICD-O-3). Following their work, the 198 currently identified rare cancers can be grouped into the following 12 families of rare cancers: central nervous system, digestive, endocrine organ, female genital, haematological, head and neck, male genital and urogenital, neuroendocrine tumours, paediatric cancers, sarcomas, skin, and thoracic rare cancers (including malignant mesothelioma). These families of rare cancers are relevant for the organization of health care.
The global aim of the Rare Cancers Working Group is to take advantage of the EPIC biorepository and detailed epidemiological annotations to better understand the etiology of these diseases and identify candidate biomarkers for diagnosis and early detection. To achieve this goal, the Working Group has started to build a centralized overview of the biological specimens and questionnaire information available for the 12 families of rare cancers, which will be available to the whole scientific community.
Contact details/Working Group leader
Saverio Caini, MD, MPH
Institute for the Study and Prevention of Cancer
Via Cosimo Il Vecchio, 2
50139 FLORENCE
Italy
s.caini@ispro.toscana.it