Prediagnostic Urinary Tract-Related Manifestations and Recurrence Risk in Colorectal Cancer with Bladder Involvement.

Background/Objectives: Colorectal cancer (CRC) with bladder involvement represents a distinct subgroup of locally advanced disease frequently accompanied by urinary tract-related manifestations (UTRMs). However, the clinical relevance of prediagnostic UTRMs in this high-risk population remains unclear. This study investigated the association between UTRMs and oncologic outcomes in patients with bladder-involved CRC. Methods: We conducted a population-based retrospective cohort study using the National Health Insurance Research Database and Catastrophic Illnesses Database (2000-2020). A total of 2608 patients with CRC involving the bladder were included. Patients with prediagnostic UTRMs, including urinary frequency, urgency, dysuria, hematuria, and urinary tract infections, were identified using diagnostic codes recorded within 6 months before CRC diagnosis. Inverse probability of treatment weighting was applied to balance baseline characteristics. Patients were followed from CRC diagnosis until disease recurrence, death, or end of the study period. Weighted Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Results: Patients with UTRMs had a significantly higher risk of disease recurrence than those without UTRMs (adjusted HR 1.57). Patients with UTRMs requiring antibiotic treatment exhibited an even greater recurrence risk (adjusted HR 4.17), although this finding should be interpreted cautiously because of the limited sample size. Associations between UTRMs and recurrence were generally consistent across subgroup analyses. In contrast, UTRMs were not significantly associated with CRC-specific mortality. Conclusions: Prediagnostic UTRMs were associated with an increased risk of recurrence in patients with CRC involving the bladder. These readily obtainable preoperative clinical manifestations may provide supplementary information for postoperative surveillance in this high-risk population. Further studies are warranted to validate these findings.