Subsequent risk of nasopharyngeal carcinoma among patients with allergic rhinitis: a nationwide population-based cohort study.

BACKGROUND The purpose of this study was to examine the risk of nasopharyngeal carcinoma (NPC) after a diagnosis of allergic rhinitis. METHODS We identified 67,532 patients with allergic rhinitis (allergic rhinitis cohort) and a 135,064 control cohort with the same mean age and sex ratio by using a Taiwan Longitudinal Health Insurance Database (LHID) sample from 2000 to 2005. RESULTS After adjusting for the possible confounding factors of the study, the allergic rhinitis cohort had a 2.33-fold higher risk of developing NPC than did the comparison cohort. The frequency of allergic rhinitis visits was correlated with the risk of subsequent NPC. Patients with 4 or more allergic rhinitis visits per year were significantly associated with increasingly developing NPC risk. CONCLUSION Patients with allergic rhinitis might be associated with subsequent NPC in Taiwan. Those who had repeated visits for allergic rhinitis had even higher risk for NPC. Physicians should be aware of the link when assessing patients with allergic rhinitis.