Hypothesis / aims of study
Overactive bladder and urinary tract cancers have increased worldwide, and both are frequently observed in the elderly population. Some studies have shown that symptoms of overactive bladder might be a lower risk factor for urinary tract cancers [1,2]; however, the exact association between overactive bladder and urinary tract cancers remains unclear. We investigated the incidence of urinary tract cancers in patients with overactive bladder as compared to those with urolithiasis to clarify whether overactive bladder is associated with urinary tract cancers.
Study design, materials and methods
This retrospective study included patients who were treated and followed up for overactive bladder or urolithiasis between January 2013 and December 2022. Overactive bladder was defined as the presence of overactive bladder symptoms using the overactive bladder symptom score in the absence of urolithiasis and urinary tract infection. Patients with a past history of urinary tract cancers were excluded. Patients were followed up regularly after initial treatment, and their incidental malignancies were treated in cases of urinary tract cancer detection during the observation period. We divided males and females into groups and analyzed the incidence of urinary tract cancers in each group.
Results
In total, 650 patients with overactive bladder (275 males and 375 females) and 2606 patients with urolithiasis (1879 males and 727 females) were analyzed. In the male group, the incidence of urinary tract cancers in the patients with overactive bladder was 4 cases (1.5%; prostate cancer in 3 and bladder in 1), which was lower than that in 62 cases (3.3%) of the patients with urolithiasis but not significant (p=0.13, OR 0.43, 95% CI 0.11-1.17, Table 1). However, age-adjusted analysis showed significance (p<0.001, OR 0.050, 95% CI 0.013-0.14, Table 2). In the female group, the incidence of urinary tract cancers in the patients with overactive bladder was 3 cases (0.8%; renal cancer in 1, upper urinary tract cancer in 1 and bladder cancer in 1) as compared to 9 cases (1.2%) of the patients with urolithiasis (p=0.76, OR 0.65, 95% CI 0.11-2.63, Table 1). Age-adjusted analysis showed no significance (p=0.22, OR 0.37, 95% CI 0.063-1.56, Table 2).
Interpretation of results
The most interesting result of this study was a significantly lower incidence of urinary tract cancers in male patients with overactive bladder. It is well-matched with previous studies showing a lower incidence of prostate cancer in patients with symptoms of overactive bladder [1,2]. These results suggest that overactivity in the bladder might not affect the oncogenesis of urinary tract cancers. For those patients, screening for urinary tract cancers including ultrasound sonography or urine cytology could not be necessary.