Urinary tract diseases and bladder cancer risk: A case-control study

Objective: The role of urinary tract diseases in bladder cancer (BC) etiology is not well established. To gain more insight on the role of urinary tract diseases in bladder cancer risk, we analyzed data from a large case-control study of bladder cancer. Methods: Epidemiological data were collected via in-person interview. Logistic regression analyses were used to estimate BC risk in association with prior history of urinary tract diseases. Results: A total of 659 BC patients and 689 age-, gender-, -ethnicity matched controls were included in the analyses. Increased bladder cancer risk was associated with history of cystitis (OR = 1.52, 95% CI: 1.12, 2.06), however, the risk was attenuated for infections diagnosed >1 year from the time of BC diagnosis or interview. In contrast, a history of four or more kidney infections was associated with a significant decreased risk of BC (OR=0.17, 95% CI: 0.04, 0.69), and there was a significant dose-response relationship between number of episode and BC risk (P for trend = 0.002). The joint effect of smoking with cystitis, kidney infection, bladder stone, kidney stone, and prostate infection was studied but revealed no significant interaction between smoking and these urinary tract diseases. Conclusion: This study does not support the concept that urinary tract infections play a major role in the development of BC. Our study has the strength of collecting diagnosis time data of urinary tract diseases to allow analyzing the impact of timing of diagnosis between cancer and urinary tract diseases. This enables us to effectively address the issue of detection bias in case-controls studies of prior urinary diseases and BC.