ESTRO 2024 - Abstract Book

S2856

Interdisciplinary - Health economics & health services research

ESTRO 2024

trimodality therapy and cystectomy patients (2). This study uses decision analysis to combine cancer outcomes and quality of life data, and aims to compare quality-adjusted life expectancy between trimodality therapy and radical cystectomy for MIBC.

Material/Methods:

Survival and progression data were extracted from Kaplan-Meier curves of the Zlotta et al. multi-institutional study (1) using WebPlotDigitizer. The extracted data were imported into R (version 4.0.2). Parametric survival models using Weibull distributions were fitted to the survival data using the survreg function. The Weibull parameters were imported into TreeAge Pro 2023 for partitioned survival analysis. Health states were classified as "Pre-Progression," "Post-Progression," and "Death," each assigned specific health utility values. Utility values were from a cross sectional study that evaluated long-term quality of life in survivors of MIBC using validated instruments (2). The primary outcome of quality adjusted life years (QALYs). The partitioned survival model was run over 10 years. Model variance and uncertainty was addressed through one-way and probabilistic sensitivity analyses with Monte Carlo simulations.

Results:

Trimodality therapy was associated with mean QALYs of 7.59 (95% CI 7.61 – 7.57) while radical cystectomy was associated with mean QALYs of 6.33 (95% CI 6.30 - 6.36). Thus, trimodality therapy improved mean incremental QALYs, with an increase of 1.26 (95% CI 1.23 - 1.30). Trimodality therapy was preferred in 70% of simulations over cystectomy using an indifference threshold of 0.5 QALYs. On one way sensitivity analyses, the model was very sensitive changes in overall survival and metastases-free survival, where changes as small as 1% survival could change the preferred strategy.

Conclusion:

Trimodality therapy was associated with higher quality-adjusted life expectancy compared to radical cystectomy in MIBC. However, the model was sensitive to small differences in survival, underscoring that differences in treatment efficacy can significantly impact net QALYs. For properly selected patients expected to have similar oncologic outcomes with either modality, therapeutic strategies should align with individual patient values and preferences.

Keywords: Bladder cancer, decision analysis, QALYs

References:

1) Zlotta AR, Ballas LK, Niemierko A, Lajkosz K, Kuk C, Miranda G, Drumm M, Mari A, Thio E, Fleshner NE, Kulkarni GS, Jewett MAS, Bristow RG, Catton C, Berlin A, Sridhar SS, Schuckman A, Feldman AS, Wszolek M, Dahl DM, Lee RJ, Saylor PJ, Michaelson MD, Miyamoto DT, Zietman A, Shipley W, Chung P, Daneshmand S, Efstathiou JA. Radical cystectomy versus trimodality therapy for muscle-invasive bladder cancer: a multi-institutional propensity score matched and weighted analysis. Lancet Oncol. 2023 Jun;24(6):669-681. doi: 10.1016/S1470-2045(23)00170-5. Epub 2023 May 12. PMID: 37187202.