Letter to the Editor Urinary Bladder Cancer Risk Factors in Egypt—Letter

In the journal, Zheng and colleagues reported a weaker bladder cancer risk for active than passive smoking based on results from a case–control study in Egypt (1). In total, 1,886 pathologically confirmed cases with urothelial cell or squamous cell carcinoma (SCC) of the bladder and 2,716 controlswere included.Control subjectswere select-edusing randomsampling of households andhealth units via family health records. Participation rates were higher for controls than cases. Unconditional logistic regression analyses were calculated adjusting for governorate of residence, urban/rural residence, age, education, urinary tract infections other than schistosomiasis, and meno-pause status (among women). Other risk factors, for example, occupational exposure to aromatic amines,were not assessed