Risk factors for upper and lower urinary tract cancer death in a Japanese population: Findings from the Japan collaborative cohort study for evaluation of cancer risk (JACC Study)

Background: The incidence of bladder cancer is lower in Asian than in Western countries. However, the crude incidence and mortality of bladder cancer have recently increased in Japan because of the increased number of senior citizens. We have already reported risk factors for urothelial cancer in a large population-based cohort study in Japan (JACC study). However, we did not evaluate the cancer risk in the upper and lower urinary tract separately in our previous study. Materials and Methods: Here we evaluated the risk of cancer death in the upper and lower urinary tracts, separately, using the database of the JACC study. The analytic cohort included 46,395 males and 64,190 females aged 40 to 79 years old. The Cox proportional hazard model was used to determine hazard ratios and their 95% confidence intervals. Results: Current smoking increased the risk of both upper and lower urinary tract cancer deaths. A history of kidney disease was associated with an increased risk of bladder cancer death, even after controlling for age, sex and smoking status. Conclusions: The present study confirmed that current smoking increases the risk of both upper and lower urinary tract cancer deaths and indicated the possibility that a history of kidney disease may be a risk factor for bladder cancer death in the Japanese population.