Tobacco smoking, alcohol drinking, and the risk of different histological types of nasopharyngeal cancer in a low-risk population

Nasopharyngeal carcinoma (NPC) is rare in western Countries. Tobacco smoking is a well-recognised risk factor, whereas the role of alcohol drinking is still in debate. We conducted a hospital-based case-control study in Italy on 150, histologically-confirmed, NPC cases of Caucasian ethnicity, aged 18-76years, including 118 undifferentiated NPCs and 22 differentiated squamous-cell NPC. Controls were 450 Caucasian cancer-free patients admitted to general hospitals for acute conditions. Cases and controls were matched according to sex, age, and place of residence. Logistic regression was used to estimate odds ratios (OR) and the corresponding 95% confidence intervals (CI) while adjusting for known confounders. No significant association emerged between tobacco smoking and all NPCs (OR for current vs. never smokers=1.52; 95% CI: 0.89-2.60). Conversely, for differentiated NPC only, statistically significant elevated OR were associated with increasing smoking intensity (OR for ⩾15cigarettes/day=5.40; 95% CI: 1.34-21.76) and duration of the habit (OR for ⩾32years=4.48; 95% CI: 1.11-18.04). Although alcohol drinking was not, per se, significantly associated to NPC risk, the combination of tobacco smoking and alcohol drinking accounted for 57% of differentiated NPCs, whereas it accounted for only 14% of undifferentiated carcinomas. Our findings suggest that, in western populations, NPC includes two separate entities: the differentiated NPC, associated with tobacco smoking like other cancers of head and neck, and the undifferentiated NPC, upon which tobacco smoking has little or no influence.