Urinary tract infections have been linked with urinary tract cancer, but the association remains controversial. We examined if pyelonephritis is a clinical marker of urogenital cancer.
We used Danish medical databases to create a population-based cohort of patients with an incident hospital-based pyelonephritis diagnosis during 1994-2013. Follow-up for cancer began at pyelonephritis diagnosis and ended on November 30, 2013. We restricted to patients older than 50 years, as urogenital cancer risk in the younger population is low. We calculated the absolute risk of urogenital cancer and the standardized incidence ratio (SIR) comparing risk observed in pyelonephritis patients to risk expected in the general population of Denmark.
Among 15,070 patients with pyelonephritis, we observed 197 urinary tract cancers and 374 genital organ cancers over a 20-year follow-up period. The absolute risk of urogenital cancer was 1.5% 6 months after a pyelonephritis diagnosis, and the cumulative risk was 3.0% at 5 years. During the first 6 months following a pyelonephritis diagnosis, the SIR of urogenital cancer was 8.56 [95% confidence interval (CI): 7.49-9.75]. Between 6 and 12 months following this diagnosis, the SIR was 1.75 (95% CI: 1.26-2.35), and beyond one year the SIR was approximately unity for most cancers. Notably, the SIR for bladder cancer among women remained elevated beyond one year of follow-up.
Patients presenting with a hospital-based diagnosis of pyelonephritis had a higher 6-months risk of urogenital cancer than expected. However, causation cannot be inferred due to the study design.
Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. 2018 Apr 11 [Epub ahead of print]
Kirstine Kobberøe Søgaard, Katalin Veres, Mette Nørgaard, Jens Christian Djurhuus, Henrik Toft Sørensen
Department of Clinical Epidemiology, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark. Electronic address: ., Department of Clinical Epidemiology, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.