Presenting postoperative mortality as percentages and natural frequencies (1-in-N) in major urologic cancer surgeries

BACKGROUND: Perioperative mortality is usually reported as percentages, although the same risk can also be expressed as natural frequencies (e.g., 1-in-N). Presenting both formats may provide complementary ways of communicating perioperative risk in clinical settings. OBJECTIVE: To compare 30- and 90-day mortality across major urologic cancer surgeries when expressed as percentages and natural frequencies, and to provide descriptive benchmarks for perioperative risk communication. METHODS: We conducted a literature-based review of national, multinational, and large-scale cohort datasets reporting perioperative mortality after radical nephrectomy (RN), partial nephrectomy (PN), radical nephroureterectomy (RNU), radical cystectomy (RC), and radical prostatectomy (RP), alongside a retrospective real-world cohort from the AGEHA database. RESULTS: Across all procedures, mortality risk ranged from 0.02% to 2.70% at 30 days and from 0.07% to 5.57% at 90 days, corresponding to natural frequencies from 1-in-5,577 to 1-in-37 patients. Radical cystectomy showed the highest perioperative mortality (30-day 1.83%, 1-in-55; 90-day 3.83%, 1-in-26), whereas radical prostatectomy showed the lowest (30-day 0.12%, 1-in-820; 90-day 0.21%, 1-in-482). The 90/30-day mortality ratio, presented as a descriptive indicator of delayed postoperative risk, varied across procedures from 1.04 in RN to 2.56 in RNU. Residual heterogeneity and possible overlap between datasets remain limitations. CONCLUSIONS: Percentages and natural frequencies provide mathematically equivalent but complementary ways of presenting postoperative mortality. Reporting both formats alongside international benchmark estimates may support clearer risk communication and contextual interpretation in urologic oncology.