The Association Between Renal Function Decline and the Incidence of Urothelial Carcinoma: A 16-year Retrospective Cohort Study in Taiwan

BACKGROUND: The incidence of cancer is higher among patients with end-stage renal disease but it remains uncertain whether a mild decrease in renal function affects cancer. OBJECTIVE: To measure the effect of impaired renal function, represented by the estimated glomerular filtration rate (eGFR), personal health behaviors, and long-term exposure to fine particulate matter (PM(2.5)) on the risk of urothelial carcinoma (UC) incidence. DESIGN, SETTING, AND PARTICIPANTS: We performed a population-based cohort study of 372 008 participants aged ≥30 yr with no prior cancer history using the MJ health examination database (2000–2015) and UC diagnosis data from the Taiwan Cancer Registry database. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Cox proportional hazards models were used to quantify the association between eGFR and UC incidence. RESULTS AND LIMITATIONS: We detected 383 UC cases during a median follow-up of 10.3 yr. Low eGFR was significantly associated with UC (p value for trend <0.01): compared to eGFR ≥90 ml/min/1.73 m(2), the adjusted hazard ratio (HR) was 1.36 (95% confidence interval [CI] 0.98–1.88), 1.86 (95% CI 1.22–2.84), and 1.95 (95% CI 1.06–3.56) for eGFR strata of 60–89, 45–59, and <45 ml/min/1.73 m(2), respectively. The risk remained elevated after stratifying the follow-up duration to check for reverse causality, and the dose-response relationship was stronger for women than for men. Current smoking (HR 1.34, 95% CI 1.02–1.77) and long-term exposure to PM(2.5) concentrations ≥25.1 μg/m(3) (HR 1.54, 95% CI 1.14–2.09) both significantly increased the risk of UC incidence. A significant dose-response relationship between PM(2.5) and UC was also noted (p(trend) < 0.01). Limitations include the retrospective design and limited information on medical history. CONCLUSIONS: Lower renal function showed a dose-response relationship in elevating UC risk. Long-term exposure to PM(2.5) is also a possible UC risk factor. PATIENT SUMMARY: People with kidney function that is lower than normal should monitor the health of their kidneys and other organs in the urinary system. Our study confirmed that as well as smoking, exposure to fine particulate matter in the air may be a risk factor for cancers of the urinary system.