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Background: The potential effect of alcohol or tea intake on the risk of nasopharyngeal carcinoma (NPC) remains controversial. Methods: In a population-based case-control study in southern China, we assessed alcohol or tea intake from 2,441 histopathologically confirmed NPC cases and 2,546 controls. We calculated mean daily ethanol (g/day) and tea intake (mL/day). Fully adjusted ORs with 95% confidence intervals (CI) were estimated using logistic regression; potential dose-response trends were evaluated using restricted cubic spline analysis. Results: Compared with nondrinkers, no significantly increased NPC risk in men was observed among current alcohol drinkers overall (OR, 1.08; 95% CI, 0.93-1.25), nor among current heavy drinkers (OR for =90 g/day ethanol vs. none, 1.32; 95% CI, 0.95-1.84) or former alcohol drinkers. Current tea drinking was associated with a decreased NPC risk (OR, 0.73; 95% CI, 0.64-0.84). Compared with never drinkers, those with the low first three quintiles of mean daily current intake of tea were at significantly lower NPC risk (OR, 0.53, 0.68, and 0.65, respectively), but not significant for the next two quintiles. Current daily tea intake had a significant nonlinear dose-response relation with NPC risk. Conclusions: Our study suggests no significant association between alcohol and NPC risk. Tea drinking may moderately reduce NPC risk, but the lack of a monotonic dose-response association complicates causal inference. [ABSTRACT FROM AUTHOR]

Background: The association between oral health and risk of nasopharyngeal carcinoma (NPC) is largely unknown. Further understanding could shed light on potential pathogenic mechanisms and preventive measures. Methods: We conducted a population-based case-control study in southern China between 2010 and 2014. We enrolled 2,528 incidentNPCcases, aged 20-74 years, and 2,596 controls, randomly selected from the total population registers, with frequency matching to the 5-year age and sex distribution of the cases by geographic region. We interviewed subjects using a structured questionnaire inquiring about oral health indicators and potential confounding factors. We used unconditional logistic regression to estimate multivariate- adjusted ORs with 95% confidence intervals (CI). Results: A higher number of filled teeth was associated with an elevated risk of NPC. Individuals with 1 to 3 and more than 3 teeth filled versus none had adjusted ORs of 1.25 (95% CI, 1.06-1.49) and 1.55 (95% CI, 1.13-2.12), respectively (Ptrend = 0.002). Conversely, the adjusted OR for those who brushed teeth twice or more per day versus once or less per day was 0.62 (95% CI, 0.55-0.70). We detected a borderline significant positive association with earlier age at first adult tooth loss. Conclusion: Our study suggested a positive association between some indicators of poor oral health and risk of NPC. Further studies are needed to confirm whether the findings are causal and, if so, to further explain the underlying mechanisms. Impact: Improvement of oral hygiene might contribute to reducing NPC risk. [ABSTRACT FROM AUTHOR]