Abstract
AbstractA cancer is considered rare when the annual cancer incidence is less than 6 per 100,000 inhabitants. In absolute numbers more than 500,000 patients per year are diagnosed with a rare cancer, and 4,300,000 rare cancer patients are prevalent in Europe. The definition is widely adopted among the different scientific international societies like ESMO and ESTRO. This means that 22% of all diagnosed cancers are rare and out of the 260 cancer types identified (www.rarecare), 223 (86%) are rare. The European Network for Rare Solid Cancers (EURACAN) uses this definition to create reference networks in order to improve rare cancer care.In Europe rare cancer patients have poorer survival as compared to common cancer patients. Moreover, the survival of rare cancer patients in the Netherlands has barely increased over time (from 50% in 1995–2000 to 56% in 2012–2016), in contrast to the common cancers (from 59% in 1995–2012 to 72% in 2012–2016). Clinical decision-making is more problematic in the case of a rare cancer because clinical studies on that tumor will be more difficult to do; so, the quality of available evidence tends to be limited. Furthermore, the decreased survival is partly caused by a delay in the diagnostic trajectory and found to be related to more advanced staging resulting in less effective treatment options.Examples of rare cancers in the head and neck region are salivary gland cancers, which can be divided in 22 histological subtypes, and epithelial tumors of the nasal cavity and sinuses, e.g. intestinal type adenocarcinoma. Furthermore, soft tissue sarcoma and bone sarcoma and Merkel cell carcinoma, which are rare and frequently located in the head and neck area (Table 20.1).New developments in the treatment of (recurrent/metastatic) salivary gland cancer, especially salivary duct cancer, will be discussed. By unraveling tumor characteristics, such as genetic alterations and protein expression profiles, therapeutic strategies tailored to the patient’s tumor can be rationalized. This genomic profiling and mapping of immunohistochemical expression profiles is essential in the search for a suitable treatment or study approach. Thereby, it alleviates the paucity in systemic treatment options and can significantly alter the prognosis of patients with rare cancers.
Highlights
Introduction on Rare tumorsDefinition and Frequency of Rare CancersRare cancers are the rare diseases in oncology needing specific approaches by the cancer community and national health systems [1]
Common challenges posed in rare cancers are a late or incorrect diagnosis [5], less experience and a limited number of experts in the field, limited number of clinical studies, less registered medications, a limited number of guidelines and less registries and biobanks
Phase III studies performed in the head and neck cancer field frequently include the epithelial cancers of the larynx, hypopharynx, oropharynx and oral cavity together, thereby making them ‘less rare’
Summary
Rare cancers are the rare diseases in oncology needing specific approaches by the cancer community and national health systems [1]. The reason why the definition is based on incidence and not on prevalence is, among others, that incidence does not change on other factors than frequency, i.e. not on survival At this moment rare molecular subgroups of common cancers are not included in the rare cancers list. The definition is widely adopted among the different scientific international societies like the European Society of Medical Oncology (ESMO) and the European Society for Radiotherapy and Oncology (ESTRO). This means that 22% of all diagnosed cancers are rare and out of the 260 cancer types identified [2], 223 (86%) are rare.
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