Session Item

Patients with spinal metastases have a range of palliative treatment options, including radiotherapy and radiofrequency ablation (RFA).  Recent data has shown higher complete pain response with SBRT in comparison to standard palliative RT.  We seek to assess the cost-effectiveness of stereotactic body radiation therapy (SBRT, 24 Gy in 2 fractions), conventional palliative external beam radiation (EBRT, 8 Gy in 1 fraction) and RFA.  

A Markov state transition model was constructed comparing the following three treatment strategies: single-fraction EBRT, two-fraction SBRT, and RFA for palliative treatment of painful spinal metastases.  Model parameters were derived from prospective clinical trial data whenever possible (Table 1). Strategies were compared using the incremental cost-effectiveness ratio (ICER), with effectiveness in quality-adjusted life years (QALYs) and a willingness-to-pay (WTP) threshold of $100,000 per QALY gained. Costs included both hospital and professional costs using 2020 Medicare reimbursement.  

The base case analysis demonstrated that 2 fractions of SBRT was not cost-effective compared to a strategy of EBRT single fraction for painful spinal metastases, with an ICER of $194,145/QALY gained.  RFA was a dominated treatment strategy (more costly and less effective) in this model.  In one-way sensitivity analyses, results were most sensitive to variation of the pain complete response rates after initial treatment with SBRT and EBRT.  Probabilistic sensitivity analysis demonstrated that EBRT was favored in 66% of model iterations at a WTP threshold of $100,000/QALY gained (Figure 1).  In addition, scenario analyses were performed reflecting current clinical practice.  First, EBRT was instead delivered with 20 Gy in 5 fractions.  In this setting, SBRT approached cost-effectiveness, with an ICER of $139,385/QALY gained.  Next, if median survival were improved after SBRT, two-fraction SBRT became cost-effective, with ICER of $80,394, $57,062, and $47,038 for 3, 6, and 9-month improvements in survival.  Because two-fraction SBRT data reported 18% of patients with indeterminant pain response at 3 months, and two-fraction SBRT is infrequently used in clinical practice, single-fraction SBRT data was also assessed.  Single-fraction SBRT delivering 24 Gy was cost-effective compared to single-fraction EBRT, with an ICER of $92,833/QALY gained.  Notably, the pain complete response rate was equivalent in the Sahgal et al. and Sprave et al. trials when patients with indeterminant pain response were excluded.    

Efforts to optimize patient selection for spine SBRT are still required, but for appropriately chosen patients, single-fraction SBRT is more cost-effective than either conventional radiotherapy or RFA.  Conventional EBRT remains a cost-effective treatment for patients with poor expected survival.