Re: Risk of urinary tract cancers following kidney or ureter stones.

BACKGROUND A relationship has been suggested between kidney or ureter stones and the development of urinary tract cancers. In this study, a population-based cohort of patients hospitalized for kidney or ureter stones in Sweden was followed for up to 25 years to examine subsequent risks for developing renal cell, renal pelvis/ureter, or bladder cancer. METHODS Data from the national Swedish In-patient Register and the national Swedish Cancer Registry were linked to follow 61,144 patients who were hospitalized for kidney or ureter stones from 1965 through 1983. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were computed on the basis of nationwide cancer incidence rates, after adjustment for age, sex, and calendar year. RESULTS Risk of renal cell cancer was not elevated in this cohort. Significant excesses of renal pelvis/ureter cancer (SIR = 2.5; 95% CI = 1.8-3.3) and bladder cancer (SIR = 1.4; 95% CI = 1.3-1.6) were observed, but the SIRs for women were more than twice those for men. Risks varied little by age or duration of follow-up. Risks of renal pelvis/ureter cancer and bladder cancer among patients with an associated diagnosis of urinary tract infection were more than double those among patients without such infection, although the risks were significantly elevated in both groups. CONCLUSIONS Individuals hospitalized for kidney or ureter stones are at increased risk of developing renal pelvis/ureter or bladder cancer, even beyond 10 years of follow-up. Chronic irritation and infection may play a role, since kidney or ureter stones were located on the same side of the body as the tumors in most patients with renal pelvis/ureter cancer evaluated in our study.