Risk factors for urinary bladder carcinoma in postmenopausal women: The Iowa Women's Health Study

BACKGROUND. We evaluated prospectively the association of smoking and other potential risk factors with bladder carcinoma incidence in postmenopausal women. METHODS. A total of 37,459 women participating in the Iowa Women's Health Study completed baseline questionnaires in 1986 and were followed 13 years for bladder carcinoma incidence (n = 112). RESULTS. Adjusted for potential confounders, the relative risk (RR) of bladder carcinoma in women who were current smokers compared with those who had never smoked was 3.58 (95% confidence interval [CI] = 1.86-6.88). The RR declined as years since quitting increased. Currently, married women, compared with unmarried women, had a RR of 0.66 (95% CI = 0.44-0.99). A 2.46-fold (95% CI = 1.32-4.59) increase in bladder carcinoma risk was identified for women who reported, versus did not report, diabetes. Regular versus no physical activity (RR = 0.66, 95% CI 0.43-1.01) and body mass index were inversely associated (P = 0.06) with bladder carcinoma incidence. CONCLUSIONS. We confirmed that cigarette smoking is an important risk factor for bladder carcinoma in women; women who had quit smoking had a reduction of risk. We also identified diabetes as a potential risk factor, which may invite more research on its role in the development of urinary bladder carcinoma.