The observational clinical registry (cohort design) of the European Reference Network on Rare Adult Solid Cancers: The protocol for the rare head and neck cancers.

The registry initiated recruiting in May 2022. The estimated completion date is December 2030 upon agreement on the achievement of all the registry objectives. As of October 2022, the registry is recruiting. There will be a risk of limited representativeness due to the hospital-based nature of the registry and to the fact that hospital contributing to the registry are expert centres for these rare cancers. Clinical Follow-up could also be an issue but active search of the life status of the patients will be guaranteed.