My cousin, who lives in Hong Kong, has been told he has a cancer of his nasopharynx. Can you tell us what the nasopharynx is?

The nasopharynx is a cube shaped space at the back of the nose and the top of the throat. It forms a passageway for air to pass from the nose to the throat, and on to the lungs.

The front of the nasopharynx is the back of the nasal septum (the thin wall of bone and cartilage that separates the two nostrils) and the nostrils. The floor of the nasopharynx is the upper surface of the soft palate, at the back of the mouth.

The roof of the nasopharynx is formed by the bones of the skull which curve backwards to form the back wall of the cavity as it drops down into the throat (the pharynx) at the back of the mouth.

Along the roof of the nasopharynx and part of the back wall there is a collection of lymphatic tissue known as the nasopharyngeal tonsil, or the adenoids. In the right and left hand walls of nasopharynx there is the opening of the eustachian tube, which is a canal that leads through the skull to the inner ear.

The nasopharynx is lined by a thin lining of epithelial cells.

Cancers of the nasopharynx may develop in these lining cells (and are the called nasopharyngeal carcinomas) or from the lymphatic tissue (in which case they are called lymphomas).