Impact of Preoperative Plasma Potassium Levels on Oncological Outcomes, Major Complications, and 30-Day Mortality in Bladder Cancer Patients Undergoing Radical Cystectomy

Introduction and Objectives

We examined the impact of preoperative plasma potassium levels (PPLs) on outcomes in patients undergoing radical cystectomy (RC) for urothelial carcinoma of the bladder (UCB), hypothesizing that potassium imbalances might influence outcomes.

Patients and Methods

In this retrospective study, 501 UCB patients undergoing RC from 2009 to 2017 at a tertiary center were analyzed. Blood samples collected a week prior to surgery defined normal and abnormal PPL based on institutional standards. We assessed overall survival (OS), cancer-specific survival (CSS), recurrence-free survival (RFS), postoperative complications, 30-day mortality, and non-organ confined disease. Kaplan-Meier estimates, Cox proportional hazards, logistic regression, and decision curve analyses (DCA) were employed.

Results

63 (13%) patients had abnormal preoperative PPLs, with 50 (10%) elevated and 13 (2.5%) decreased. In a 59 months median follow-up, 152 (31%) had disease recurrence, 197 (39%) died from any cause, and 119 (24%) from UCB. Multivariable cox regression analyses adjusting for perioperative parameters demonstrated abnormal PPL was associated with worse OS (HR=1.9, P=0.009), CSS (HR=2.8, P<0.001) and RFS (HR=2.1; P=0.007). Elevated preoperative PPLs also demonstrated significant associations with adverse outcomes in OS, CSS, and RFS (all P<0.05). In multivariable logistic regression analyses, abnormal and elevated PPLs were not associated with 30-day mortality, major 30-day postoperative complications, positive nodal disease, pT3/4 stage, and non-organ confined disease (all P>0.05).

Conclusion

Abnormal and elevated preoperative PPLs correlate with adverse oncologic outcomes in UCB patients treated with RC. Pending external validation, preoperative PPLs might be a cost-effective, easily obtainable supplemental biomarker for enriching accuracy of outcome prediction in this highly variable maladie.