Purpose: The Chest Radiotherapy Extensive-Stage Small Cell Lung Cancer Trial (CREST) showed that adding thoracic radiation therapy (TRT) to the standard treatment (ST) paradigm of chemotherapy and prophylactic cranial irradiation improves overall survival and progression-free survival (PFS) in patients with extensive-stage small cell lung cancer (ES-SCLC). We evaluated the cost-effectiveness of adding TRT to ST in ES-SCLC patients.
Methods and materials: A cost-utility analysis was performed comparing TRT plus ST versus ST alone. The base-case time horizon was 24 months, consistent with the maximum PFS reported in the CREST. Overall survival was partitioned into 2 health states: PFS and postprogression survival. The proportion of patients in each health state over time was estimated by fitting parametric probability distributions to the CREST survival data. Costs were from a US health care payer perspective, and utilities were derived from the literature. Incremental cost-effectiveness ratios (ICERs) were calculated per quality-adjusted life-year (QALY) using a 3% discount rate. Sensitivity analyses addressed uncertainty in key variables.
Results: In the base-case analysis, adding TRT to ST was both cost saving and more effective, thereby strongly dominating ST alone. At willingness-to-pay thresholds of $50,000/QALY, $100,000/QALY, and $200,000/QALY, TRT was preferred 68%, 81%, and 96% of the time, respectively. In the lifetime scenario analysis, the TRT ICER increased to $194,726/QALY.
Conclusions: By use of the actual follow-up interval reported in the CREST, adding TRT to ST strongly dominates a strategy of ST alone in ES-SCLC patients. Since the long-term survival benefit of TRT is small relative to ongoing costs of progressive metastatic disease, we estimate less favorable ICERs for TRT over a lifetime horizon.
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