Case-control study evaluating the homogeneity and heterogeneity of risk factors between sinonasal and nasopharyngeal cancers

Sinonasal cancer and nasopharyngeal cancer may share some risk factors because both are located within the upper aerodigestive tract. They may also have different etiological profiles because of anatomic or pathologic differences. However, the similarities and differences in risk factors have rarely been studied within the same population. We assessed the risk factor profiles of sinonasal and nasopharyngeal cancers, using data from a case-control study. The 2 case groups consisted of men aged 31-59 and diagnosed pathologically with sinonasal cancer (n=70) and nasopharyngeal cancer (n=113), respectively. Controls were men without these cancers and selected from the same areas (n=1910). Logistic regression analysis showed that smoking was a risk factor for both sinonasal [odds ratio (OR)=2.5, 95% confidence interval (C1) 1.1-5.4] and nasopharyngeal cancer (OR= 1.8, 95%C1 1.1-3.0). However, ever use of barbiturates without a prescription (OR=4.9, 95%C1 1.7-13.8), working with or around cutting oils on a job (OR= 1.9, 95%Cl 1.1-3.1) and ever having had sinus infections (OR=2.3, 95%C1 1.1 -4.6) were associated with nasopharyngeal cancer only. Having received blood products other than a transfusion (OR=9.1, 95%C1 2.2-37.4) and exposure to a pesticide containing 2,4,5-T (OR=5.9, 95%C1 1.5-23.7) were related to sinonasal cancer only. When data analyses were confined to squamous cell type, smoking and exposure to chlorophenols were related to squamous cell tumors at both sites. However, use of barbiturates and sinus problems other than infection only increased the risk of nasopharyngeal carcinoma. Our study suggests that except for smoking and chlorophenol exposure, which are associated with both sites, the risk factor profiles may differ between sinonasal and nasopharyngeal cancers.