Meta-Analysis Profiles Bladder Cancer Risks and Histology in Neurogenic Dysfunction

Adults diagnosed with neurogenic lower urinary tract dysfunction face a rare but disproportionately lethal risk of bladder cancer that characteristically manifests at an earlier age, at an advanced anatomical stage, and with an unusually high proportion of squamous cell carcinoma, according to an updated systematic review and meta-analysis published in the African Journal of Urology. Conducted by researchers Oluwatosin Gabriel Afolabi, Abiodun Idowu Okunlola, Mayowa Emmanuel Oluwajuyigbe, Adedamola Benjamin Adegbamigbe, Damilola Timothy Ishola, and Patrick Ashinze, the investigation synthesised primary studies evaluating malignancy across diverse neurogenic conditions, including acquired spinal cord injury, congenital spina bifida, and cohorts managed with augmentation cystoplasty. Across spinal cord injury cohorts providing extractable denominator data, the primary random-effects meta-analysis revealed a pooled cumulative bladder cancer occurrence of 0.35 percent, while simultaneously exposing profound statistical heterogeneity and a notable absence of empirical data from low-resource regions such as sub-Saharan Africa.

The clinical motivation for this synthesis stems from the evolving epidemiology of spinal cord injuries and related neurological disorders, where advances in acute trauma care and rehabilitation have lengthened overall patient survival over recent decades. A cited global synthesis indicated an overall spinal cord injury incidence of 23.8 per million individuals, with traumatic injury rates observed to be higher in developing countries and nontraumatic incidence climbing steadily since 2007. As survival horizons extend, long-term urological complications have assumed greater clinical prominence. In healthy, able-bodied populations, bladder cancer presents predominantly as urothelial carcinoma and typically manifests in later decades of life, heavily driven by tobacco smoking and occupational chemical exposures. In patients with neurogenic lower urinary tract dysfunction, however, bladder carcinogenesis involves distinctive chronic pathological stimuli, including mechanical irritation from indwelling catheters, recurrent urinary tract infections, chronic urinary stasis, and bladder calculi.

To rigorously evaluate the global evidence base, the investigators designed a comprehensive systematic review adhering strictly to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 statement. The methodological protocol was registered prospectively on the Open Science Framework under identifier OSF.IO/FKQN9 prior to data charting, with no substantive deviations occurring during execution. Comprehensive electronic literature searches were carried out across four major scientific databases—MEDLINE/PubMed, Embase, Scopus, and Web of Science—from their respective inception dates through May 2026. Search strings combined MeSH and thesaurus indexing terms alongside free-text terms covering neurogenic bladders, spinal cord injuries, spinal dysraphism, spina bifida, augmentation cystoplasty, indwelling catheterisation, and various bladder neoplasms, supplemented by citation tracking and manual reference list searches across relevant primary reports and guideline documents.

Eligibility criteria required primary clinical investigations—including cohort, case-control, cross-sectional, and case series encompassing three or more patients—that documented bladder cancer occurrence, tumour histology, stage or grade at diagnosis, bladder cancer mortality or standardised ratios, risk factors, or surveillance yield in adults with neurogenic lower urinary tract dysfunction. Following duplicate removal from 1,141 initial records, two reviewers independently screened 784 titles and abstracts using the Rayyan platform, demonstrating substantial inter-rater agreement with a Cohen kappa coefficient of 0.78 and 96.6 percent observed concordance. Sixty-eight retrieved full-text articles underwent independent appraisal, yielding almost perfect reviewer agreement with a kappa of 0.90 and 97.1 percent observed concordance. Disagreements were arbitrated by a third reviewer, resulting in a final corpus of 14 eligible primary studies published between 1999 and 2021.

Methodological quality across the 14 included publications was appraised using the Joanna Briggs Institute critical appraisal tools specific to prevalence studies, cohort designs, and case series. All studies originated exclusively from high-income jurisdictions: seven from Europe, including Germany, the United Kingdom, Spain, and Switzerland; six from the United States in North America; and one from Taiwan in East Asia. No study originated from sub-Saharan Africa or any other low- or middle-income setting. Study sizes ranged from fewer than 200 patients to large administrative cohorts exceeding 43,000 individuals. Methodological rigor was judged to be moderate overall, with large registry and database cohorts achieving valid case ascertainment and objective outcome assessment but exhibiting incomplete control for potential confounding variables, whereas smaller congenital case series carried higher risks of selection and reporting biases.

Five spinal cord injury cohorts furnished mutually comparable numerators and denominators, collectively reporting 243 bladder cancer cases among 89,526 individuals. The reported study-level cumulative proportions spanned from 0.11 percent to 0.57 percent. To stabilise the variance of low-event proportions, researchers pooled these data using a Freeman–Tukey double-arcsine transformation embedded in a DerSimonian–Laird random-effects model, back-transforming with the harmonic mean of sample sizes. The resulting primary pooled cumulative occurrence was 0.35 percent, with a 95 percent confidence interval spanning 0.16 percent to 0.62 percent. However, statistical heterogeneity was exceptionally high, demonstrated by an I-squared value of 95.9 percent, between-study variance tau-squared of 0.0017, and a Cochran Q statistic of 96.6 with 4 degrees of freedom (p < 0.001), indicating marked disparities in cohort composition, ascertainment windows, and follow-up duration.

A pre-specified sensitivity analysis restricted pooling to the two cohorts evaluated as having an overall low risk of bias on the Joanna Briggs Institute appraisal—specifically investigations by Groah in 2002 and Böthig in 2021, comprising 61 bladder cancer cases among 11,066 patients. In this restricted subset, the pooled cumulative proportion rose to 0.56 percent, with a 95 percent confidence interval of 0.43 percent to 0.71 percent, while between-study heterogeneity was completely eliminated, showing an I-squared of 0 percent and a Cochran Q of 0.06 with 1 degree of freedom (p = 0.80). The authors noted that older multicentre survey cohorts carrying moderate overall risk of bias and high risk within the confounding-control domain largely generated the statistical heterogeneity observed in the primary model. Because granular patient-level variables were inconsistently reported across studies, formal subgroup analyses by catheterisation mode, injury duration, or geographical origin were unfeasible.

Despite a low absolute incidence, the relative mortality and comparative risk of bladder cancer in neurogenic populations proved strikingly elevated compared with the general population. Long-term longitudinal follow-up spanning four decades documented a standardised mortality ratio of 6.7, with a 95 percent confidence interval of 5.4 to 8.1, for individuals with spinal cord injuries relative to national population benchmarks. Chronic exposure to indwelling catheters magnified these hazards substantially: one cohort documented a standardised morbidity ratio of 25.4 and a 4.9-fold relative risk compared with non-indwelling catheter management, while a population database analysis reported adjusted hazard ratios of 6.51 for spinal cord injury and 9.11 for chronic indwelling catheter use without spinal cord injury. Furthermore, a long-term single-centre cohort identified an age-standardised incidence rate of 30.7 per 100,000 person-years.

Histological evaluations revealed a profound shift toward squamous cell carcinoma compared to non-neurogenic populations. In general, nonendemic populations, squamous cell carcinoma accounts for roughly 5 percent of all bladder malignancies. By contrast, among the three neurogenic studies providing extractable histological subtype denominators, squamous tumours represented 18.9 percent (7 of 37 cases) in a multicentre survey, 33.3 percent (14 of 42 cases) in a veteran cohort, and 100 percent (4 of 4 cases) in a specialized single-centre series. Because denominators were small, heterogeneous, and derived partly from single-arm series, meta-analytic pooling of histology was avoided to prevent misleading estimates. Advanced disease stage at diagnosis was widespread: 60 percent of spinal cord injury tumours infiltrated the detrusor muscle, while spina bifida series showed that 88 percent to 100 percent of diagnosed malignancies presented with locally advanced or node-positive disease, yielding a median post-diagnosis survival of merely six months.

In evaluating diagnostic surveillance modalities, the synthesis established that routine surveillance cystoscopy and urine cytology provide low and inconsistent yields. A prospective cross-sectional study evaluating 129 patients with neurogenic lower urinary tract dysfunction spanning five or more years detected relevant histological anomalies in only 5 percent of participants and found just a single muscle-invasive carcinoma. Given the low absolute cumulative occurrence, the limited diagnostic yield of screening tests, and the procedural discomfort and risks of recurrent instrumentation, published evidence argues against blanket, universal surveillance. In their discussion, the authors stressed that because all 14 included studies were conducted in high-income settings, these statistical estimates cannot be directly extrapolated to sub-Saharan Africa. The authors highlighted a biologically plausible hypothesis that a catheter-driven inflammatory pathway could converge with endemic urogenital schistosomiasis—a known Group 1 carcinogen—to accelerate aggressive squamous cell carcinomas, urging future region-specific research rather than the uncritical adoption of high-income surveillance strategies.

Subject of Research: Systematic review and meta-analysis of bladder cancer risk, histology, and surveillance in neurogenic lower urinary tract dysfunction

Article Title: Bladder cancer risk, histological pattern, and surveillance in adults with neurogenic lower urinary tract dysfunction: an updated systematic review and meta-analysis with implications for sub-Saharan Africa

Article References: Afolabi, O. G., Okunlola, A. I., Oluwajuyigbe, M. E., Adegbamigbe, A. B., Ishola, D. T., & Ashinze, P. (2026). Bladder cancer risk, histological pattern, and surveillance in adults with neurogenic lower urinary tract dysfunction: an updated systematic review and meta-analysis with implications for sub-Saharan Africa. African Journal of Urology, 32(1), Article 54. https://doi.org/10.1186/s12301-026-00603-4

Image Credits: AI Generated

DOI: 10.1186/s12301-026-00603-4

Keywords: bladder cancer, neurogenic bladder, spinal cord injury, spina bifida, squamous cell carcinoma, systematic review, meta-analysis, urology, indwelling catheter, cancer surveillance, Bladder, cancer