What is a rare cancer?

Cancer is considered to be rare when its incidence is less than 6 cases per year per 100,000 inhabitants, indicates the National Cancer Institute. A cancer is also considered rare if it is located in a specific and unusual place (the thymus, uvea or digestive tract for example, or if it occurs in a specific context (during pregnancy for example) or if it is particularly complex, little known and requiring highly specialized care.The term ‘rare cancer’ is unfortunatebecause if we group them together, they concern 22% of all cancer patients (either 70,000 cases each year in France)“, notes Dr Charles Honoré, visceral surgeon and head of the “Bone – Soft Parts” committee at Gustave Roussy. Not all rare cancers are necessarily aggressive or poor prognosis (for example, the survival observed after 5 years for children aged 0 to 14 years who have retinoblastoma is 96%). They are not necessarily hereditary either. However, genetic abnormalities predispose to certain rare cancers: this is the case of von Hippel-Lindau disease or certain rare neuroendocrine cancers.

The list of rare cancers

The list of rare cancers has been established according to the classification published in 2011 by the RARECARE working group, in charge of monitoring rare cancers in Europe. Here are several examples:

► Pediatric cancers: retinoblastoma, neuroblastoma, medulloblastoma

► Hematological cancers: classical Hodgkin lymphoma, chronic myelogenous leukemia, mastocytosis, Fanconi anemia…

► Environmentally linked cancers

► Rare thoracic cancers: tumors of the thymus, tumors of the trachea and lung…

► Rare skin or eye cancers: Gorlin syndrome, Cowden syndrome…

► Rare cancers of the digestive sphere: Paget’s disease of the anal canal, intrahepatic cholangiocarcinoma, familial adenomatous polyposis, etc.

► Rare gynecological cancers: Paget’s disease of the breast, breast cancer in men, Li-Fraumeni syndrome…

► Rare ENT cancers: head and neck tumor of salivary gland type, neurofibromatosis type 2…

► Sarcomas: Ewing’s sarcoma of soft tissues, Kaposi’s sarcoma…

► Neuroendocrine tumors: endocrine neoplasia, familial leiomyomatosis, etc.

► Rare tumors of the brain and central nervous system: choroid plexus carcinoma, ependymal tumors, etc.

► Rare urological cancers: adenocarcinoma of the urethra, Birt-Hogg-Dubé syndrome…

Cancers more difficult to treat

Due to their rarity or specificity, these cancers are often the subject ofa delay in diagnosis and difficulties in implementing a treatment adapted to each patient, which often requires inclusion in a clinical trial. So these are cancers more difficult to treat. This is why in 2009, the National Cancer Institute decided to better organize the provision of care for rare cancers, in order to improve the diagnostic and therapeutic care of patients. To do this, it has certified networks bringing together different care establishments coordinated by reference centers : Refcor for rare ENT cancers, Rythmic for thymus cancers, Carare for rare kidney tumors, Netsarc for sarcomas, etc.