Unveiling an Association between Waterpipe Smoking and Bladder Cancer Risk: A Multicenter Case–Control Study in Iran
AbstractBackground:. Limited data exist for the association between bladder cancers and waterpipe smoking, an emerging global public health concern.Methods:. We used the IROPICAN database in Iran and used multivariable logistic regression, adjusting for cigarette smoking, opium use, and other confounding factors. In addition, we studied the association between exclusive waterpipe smoking and bladder cancer.Results:. We analyzed 717 cases and 3,477 controls and a subset of 215 patients and 2,145 controls who did not use opium or cigarettes. Although the OR adjusted for opium, cigarettes, and other tobacco products was 0.92 [95% confidence interval (CI), 0.69–1.20], we observed a statistically significant elevated risk in exclusive waterpipe smokers (OR = 1.78; 95% CI, 1.16–2.72) compared with non-users of opium or any tobacco. Associations were strongest for smoking more than two heads/day (OR = 2.25; 95% CI, 1.21–4.18) and for initiating waterpipe smoking at an age less than 20 (OR = 2