Risk factors of nasopharyngeal carcinoma in Turkey-an epidemiological survey of the Anatolian Society of Medical Oncology.

Background: Nasopharyngeal carcinoma is a rare disease in most parts of the world with a multifactorial etiology involving an interaction of genetic, viral, environmental and dietary risk factors. This is the first epidemiologic study aimed to evaluate the risk factors of nasopharyngeal carcinoma in the Turkish population.

Methods: We conducted a multicentric, retrospective, case-control study using a standardized questionnaire which captured age, sex, occupation, household type, blood group, dietary habits, smoking, alcohol consumption and oral hygiene. The study included 183 cases and 183 healthy controls matched by sex and age. Multiple logistic regression and univariate analysis were employed.

Results: The peak age incidence was 40-50 years and the male to female ratio was 2:1. We observed significant associations between elevated nasopharyngeal carcinoma risk and low socioeconomic status, rural household type (OR:3.95, p<0.001), farming (OR:4.24, p<0.001) and smoking (OR:3.15, p<0.001). Consumption of french fries (OR:1.44, p=0.024), fried meat (OR:1.05, p=0.023) and tea (OR:5.55, p<0.001) were associated with elevated risk, while fresh fruit consumption was associated with reduced risk (OR:0.59, p=0.011). An irregular meal pattern was also a risk factor (OR:1.75, p=0.012). There were no significant associations between consumption of grain, diary products, alcohol and nasopharyngeal carcinoma risk (p>0.05); furthermore salty foods had a borderline p value (OR:2.14, p=0.053). Blood type A increased the risk (OR:2.03, p=0.002) while blood type 0 was a protective factor (OR:0.53, p=0.009). Rare habit of teeth brushing (OR:6.17, p<0.001) and ≥ 10 decayed teeth before diagnosis (OR:2.17, p<0.001) increased the risk.

Conclusions: The nasopharyngeal carcinoma risk factors described in the literature are also applicable for the Turkish population. People with type A blood are at risk in Turkey. Salted foods have also a border risk out of the endemic regions. This is the only study showing that poor oral hygiene is a serious risk factor for nasopharyngeal carcinoma.