Cost-Effectiveness of Single Versus Multifraction SABR for Pulmonary Oligometastases: The SAFRON II Trial

Abstract

The use of stereotactic ablative body radiation therapy (SABR) in advanced cancer care is increasing, yet the cost-effectiveness of single-fraction (SF) versus multifraction (MF) SABR in pulmonary oligometastases is unknown. A prespecified cost-effectiveness analysis was conducted of the Trans Tasman Radiation Oncology Group 13.01 - SAFRON II - randomized trial comparing SF with MF SABR in 87 patients with 133 pulmonary oligometastases. A partitioned survival model assessed costs and quality-adjusted life-years (QALY) over the within-trial period (4 years) and longer-term (10 years). Costs reflected a societal perspective, expressed in Australian dollars (A$) using 2020 prices and were estimated using patient level data on health care utilization for radiation therapy (including patient time), post-radiation systemic therapy and treatment of adverse effects. Quality of life was assessed using the EuroQoL EQ-5D-5L. The incremental cost-effectiveness ratio (ICER) was expressed as the cost per QALY gained for SF versus MF SABR, with uncertainty assessed using deterministic and probabilistic sensitivity analyses. SF cost less than MF for initial therapy (difference of A$1194/patient). Mean time to initiation of systemic drug therapy did not differ between arms (P=.94). Numerical differences in survival favoring SF resulted in greater overall health care use for the within-trial period. The within-trial ICER was A$15,821/QALY and A$23,265/QALY over the longer term. Results were most sensitive to the cost of postprogression therapies and utility values. The sensitivity analysis indicated that SF SABR has a 97% probability of being cost-effective at a willingness-to-pay of A$50,000/QALY. SF has lower initial costs and is highly likely to be cost-effective. Time to initiation of systemic therapy associated with disease progression is highly patient relevant and is a major driver of cost-effectiveness. Comparisons for SF SABR with nonradiation therapy approaches to the treatment of pulmonary oligometastases warrant further investigation.