Background: Nasopharyngeal carcinoma is the most common head and neck carcinoma which was the most common squamous cell carcinoma type. The etiology of nasopharyngeal carcinoma is multifactorial. Some researches has proved that salted fish contains a carcinogenic substance, such as nitrosamine, which can activate latent EBV at nasopharyngeal epithelium. This research aims to know the associatio…