Opium and Cigarette Smoking are Independently Associated with Bladder Cancer: The Findings of a Matched Case - Control Study.

Background: Bladder cancer disproportionally affects the communities. While it is the ninth most common cancer in the world, in some parts of Iran including Kerman province it is the most common cancer among men. This study aimed to determine potential risk factors of bladder cancer in Kerman province, Iran.
Methods: During February to July 2020, in this matched hospital-based case-control study, 100 patients with bladder cancer and 200 healthy individuals (matched in age and sex) were recruited. Socio-demographics status, occupational exposures, common diet, history of drug use and family history of cancer, were collected using a structured questionnaire. Bivariable and multivariable logistic regression were applied and crude and adjusted odds ratios (AOR) along with their 95% confidence intervals (95%CI) were calculated. Data were analyzed using Stata version 14 software.
Results: Opium consumption, cigarette smoking and low level of income were associated with increased chance of bladder cancer. Compared to never use, use of opium up to 18000 Gram -year was associated with increased chance of bladder cancer (AOR: 6; 95% CI =2.3, 15.5). The chance was higher among those who used opium more than 18,000 Gram - year (AOR: 11.3; 95% CI =2.3, 15.5). In comparison with never smokers, the chance of bladder cancer increased among those who smoked up to 20 pack-year cigarette) (AOR: 3.4; 95%CI= 1.3, 8.9) and those who smoke ≥ 20 pack-year (AOR: 15.8; 95% CI= 5.9, 42.4).
Conclusions: The observed strong dose-response association between opium consumption, cigarette smoking and bladder cancer highlights the need for extension of harm reduction programs especially in regions with high burden of disease.