Cost Analysis of Adjuvant Whole-Brain Radiotherapy Treatment Versus No Whole-Brain Radiotherapy After Stereotactic Radiosurgery and/or Surgery Among Adults with One to Three Melanoma Brain Metastases: Results from a Randomized Trial

Purpose We aimed to compare Australian health system costs at 12 months for adjuvant whole-brain radiotherapy (WBRT) treatment after stereotactic radiosurgery (SRS) and/or surgery versus observation among adults with one to three melanoma brain metastases. We hypothesized that treatment with adjuvant WBRT and subsequent healthcare would be more expensive than SRS/surgery alone. Methods The analysis was conducted alongside a multicentre, randomized phase III trial. A bespoke cost questionnaire was used to measure healthcare use, including hospitalizations, specialist and primary care visits, imaging, and medicines over 12 months. Mean per-patient costs were calculated based on the quantity of resources used and unit costs, reported in Australian dollars ($AU), year 2018 values. Skewness of cost data was determined using normality tests and censor-adjusted costs reported using the Kaplan-Meier sample average method. The analysis of difference in mean costs at each 2-month time point and at 12 months was performed and checked using Kruskal-Wallis, generalized linear models with gamma distribution and log link, modified Park test, ordinary least squares, and non-parametric bootstrapping. Results In total, 89 patients with similar characteristics at baseline were included in the cost analysis (n = 43 WBRT; n = 46 observation). Hospitalization cost was the main cost, ranging from 63 to 89% of total healthcare costs. The unadjusted 12-monthly cost for WBRT was $AU71,138 +/- standard deviation 41,475 and for observation $AU69,848 +/- 33,233; p = 0.7426. The censor-adjusted 12-monthly cost for WBRT was $AU90,277 +/- 36,274 and $AU82,080 +/- 34,411 for observation. There was no significant difference in 2-monthly costs between groups (p > 0.30 for all models). Conclusions Most costs were related to inpatient hospitalizations associated with disease recurrence. Adding WBRT after local SRS/surgery for patients with one to three melanoma brain metastases did not significantly increase health system costs during the first 12 months.