RESEARCH COMMUNICATION Evaluation of Non-viral Risk Factors for Nasopharyngeal Carcinoma in Thailand: Results from a Case-control Study

The incidence of nasopharyngeal carcinoma (NPC) varies widely according to geographic location and ethnic background. Over the year, numerous studies have shown that the etiology of NPC is multifunctional, including genetic, environmental, and virological factors. Among these factors, EBV seems to be the strong association between infection of EBV and NPC (International Agency for Research on Cancer, 1997). However, given the universality of EBV infection but the unique geographic distribution of NPC, factors other than EBV are also believed to be important determinants of the risk for NPC. Numerous factors have been postulated to be linked to the development of NPC, including consumption of salted and processed foods, occupational exposure to formaldehyde and dusts, and cigarette smoking (Hildesheim and Levine, 1993). Most studies of NPC have been conducted in China or among individuals of Chinese ethnicity. In Thailand, the age-standardized incidence of NPC during the period 2001-2003 was 3.7/100,000 among