Chronic catheterization may put individuals at risk of bladder cancer

Chronic indwelling or intermittent bladder catheterization contributes to an increased risk of bladder cancer and related mortality, with the highest risk observed among individuals using catheters for almost 3 years as well as those with bladder calculi, as suggested in a recent study.

Compared with the general population, patients requiring chronic indwelling or intermittent bladder catheterization were more than four times as likely to develop bladder cancer and eight times as likely to die from bladder cancer, according to Canada-based researchers. “Urinary tract infection (UTI) was also an independent predictor of bladder cancer and bladder cancer death.”

The researchers pointed to chronic inflammation as a potential mechanism underlying the elevated risk of bladder cancer observed with chronic catheterization and UTI. This is consistent with previous studies that described pathological changes including keratinising squamous metaplasia and cystitis glandularis in as many as one quarter of patients with traumatic spinal cord injury and chronic bladder catheters. [J Urol 1999;161:1106-1109]

The current study included 36,903 patients who required chronic catheterization and 110,709 matched patients without a history of catheterization (control). The median age of the overall population was 62 years, and 52 percent were female.

Over a median follow-up of 8.8 years, bladder cancer occurred more frequently in the catheter group than in the control group (1.1 percent vs 0.3 percent; p<0.001), as did bladder cancer death (0.3 percent vs 0.1 percent; p<0.001). [BMJ Open 2021;11:e050728]

Bladder cancer was associated with chronic catheterization (adjusted subdistribution hazard ratio [sdHR], 4.80, 95 percent confidence interval [CI], 4.26–5.42; p<0.001) and the number of UTIs (per episode: adjusted sdHR, 1.04, 95 percent CI, 1.04–1.05; p<0.001). Bladder cancer-specific death was also linked to chronic catheterization (adjusted sdHR, 8.68, 95 percent CI, 6.97–10.81; p<0.001).

The risk of both bladder cancer diagnosis and mortality was consistent in subgroups of patients with neurogenic bladder and bladder calculi. There was also evidence of a dose-response relationship between duration of catheterization and bladder cancer risk, with patients in the two longest catheter duration quintiles (2.9–5.9 and 5.9–15.5 years) being at the highest risk.

“To our knowledge, this is the first study to quantify the increase in risk of bladder cancer among a large, diverse group of patients and to explore the impact on bladder cancer mortality, accounting for the competing risk of death. We were also able to account for the effect of UTI in a time-varying manner,” the researchers said.

“Our study findings remained robust on sensitivity analysis accounting for potential verification bias using a second comparison group of patients with renal or ureteric calculi who would have had access to regular urological care during the study period,” they added.

Despite the relatively high rates of bladder cancer incidence and mortality, the absolute rates were low. As such, the researchers pointed out that routine screening procedures with cystoscopy and imaging tests may not be cost-effective.

The study was limited by the potential for misclassification, residual confounding, and detection bias, highlighting the need for additional studies to validate the present data. Nevertheless, it is important that clinicians managing patients with chronic catheter requirement be aware of the patients’ potential risk of developing bladder cancer, the researchers said.