Long-term risk of urinary adverse events in curatively treated patients with rectal cancer: A population-based analysis

BACKGROUND: Treatment modalities for rectal cancer, including radiation, are associated with urinary adverse effects. OBJECTIVE: The purpose of this study was to determine the influence of surgery and radiation therapy for rectal cancer on long-term urinary complications. DESIGN: Using the Surveillance Epidemiology and End Results-Medicare data set from the United States, patients with rectal cancer older than 66 years of age who underwent rectal resection between 1992 and 2007 were stratified into treatment groups that accounted for surgical resection and the timing of radiation therapy, if used. A control group of patients who did not have rectal cancer were matched by age, sex, demographics, and comorbidities. The primary outcome was a urinary adverse event defined as a relevant urinary diagnosis with an associated procedure. Patients with rectal cancer in different treatment groups were compared with control patients using a propensity-adjusted, multivariable Cox regression analysis. SETTINGS: The study was conducted with the Surveillance Epidemiology and End Results-Medicare data set from the United States at our institution. RESULTS: Of the 11,068 patients with rectal cancer, 56.2% had surgical resection alone, 21.7% received preoperative radiation, and 22.1% received postoperative radiation. The median follow-up for all of the groups of patients was >2 years. All of the groups of patients with rectal cancer were more likely to develop a urinary adverse event compared with control subjects. Adjusted HRs were 2.28 (95% CI, 2.02-2.57) for abdominoperineal resection alone, 2.24 (95% CI, 1.79-2.80) for preoperative radiation and surgical resection, 2.04 (95% CI, 1.70-2.44) for surgical resection and postoperative radiation, and 1.69 (95% CI, 1.52-1.89) for low anterior resection alone. LIMITATIONS: Treatment patterns are somewhat outdated, with a large proportion of patients receiving postoperative radiation. The data did not allow for accurate assessment of urinary tract infections or mild urinary retention that is not managed with a procedure. CONCLUSIONS: Rectal cancer surgery with or without radiation is associated with a higher risk of urinary complications requiring procedures. Patients who undergo low anterior resection without radiation tend toward the lowest risk for a urinary adverse event.