Aetiology
Risk factors for nasopharyngeal cancer (NPC) include a history of Epstein-Barr virus (EBV) infection, diet rich in preserved foods (specifically salted fish), smoking or other tobacco use, and a family history of NPC in first-degree relatives.
EBV infection is the most important risk factor for NPC. EBV DNA and EBV-latent proteins can be detected in NPC precursor lesions and tumour cells. Polymerase chain reaction (PCR) can detect circulating EBV DNA in the plasma in >95% of people with NPC.[10] The mechanism for how salted fish consumption causes NPC is not established but is thought to be due to exposure to nitrosamines and/or reactivation of latent EBV infection.[11]
A family history of NPC in first-degree relatives is associated with a relative risk of developing NPC of 6-21, compared with healthy controls based on several cohort studies.[12]
Investigating smoking as a risk factor for NPC, one meta-analysis from 2013 reported a pooled odds ratio of 1.60 (95% CI 1.38 to 1.87) from 32 studies.[13] Another meta-analysis reported a pooled odds ratio of 1.56 (95% CI 1.32 to 1.83) from 19 studies. The studies included in both meta-analyses had substantial heterogeneity.[14]
Pathophysiology
NPC (squamous cell carcinoma of the nasopharynx) arises from epithelial cells within the lymphocyte-rich nasopharyngeal mucosa. The physiological processes that lead to neoplasia of the epithelial cells include genetic susceptibility, environmental factors, and infections (particularly Epstein-Barr virus infection).
Classification
WHO classification of nasopharyngeal carcinomas[2][3]
The World Health Organization classifies nasopharyngeal carcinomas into three histopathological subtypes:
Non-keratinising squamous cell carcinoma (formerly WHO types 2 and 3 NPC, but now considered a single clinical entity)
Keratinising squamous cell carcinoma (formerly WHO type 1 NPC)
Basaloid squamous cell carcinoma (added to the WHO classification in 2005).
Use of this content is subject to our disclaimer