American Association for Cancer Research
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Supplementary Methods and Materials from Unveiling an Association between Waterpipe Smoking and Bladder Cancer Risk: A Multicenter Case–Control Study in Iran

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posted on 2024-04-09, 15:00 authored by Maryam Hadji, Hamideh Rashidian, Maryam Marzban, Abbas Rezaianzadeh, Alireza Ansari-Moghaddam, Mahdieh Bakhshi, Azim Nejatizadeh, Monireh Sadat Seyyedsalehi, Ahmad Naghibzadeh-Tahami, AliAkbar Haghdoost, Elham Mohebbi, Neal D. Freedman, Reza Malekzadeh, Arash Etemadi, Farin Kamangar, Elisabete Weiderpass, Eero Pukkala, Paolo Boffetta, Kazem Zendehdel

Tobacco questionnaire


National Institute for Medical Research Development (NIMAD)

Fondazione AIRC per la ricerca sul cancro ETS (AIRC)



Limited data exist for the association between bladder cancers and waterpipe smoking, an emerging global public health concern. 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. 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 = 2.73; 95% CI, 1.11–6.72). The OR for urothelial bladder cancer was higher in ex-smokers (OR = 2.35; 95% CI, 1.24–4.42) than in current smokers (OR = 1.52; 95% CI, 0.72–3.15). All observed associations were consistently higher for urothelial histology. Waterpipe smoking may be associated with an increased risk of bladder cancer, notably among individuals who are not exposed to cigarette smoking and opium. The study provides compelling evidence that waterpipe smoking is a confirmed human carcinogen, demanding action from policymakers.See related In the Spotlight, p. 461

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