Selective Internal Radiotherapy (SIRT) in Metastatic Colorectal Cancer Patients with Liver Metastases: Preliminary Primary Care Resource Use and Utility Results from The Foxfire Randomised Controlled Trial

The FOXFIRE trial aims to assess cost-effectiveness of selective internal radiotherapy, using yttrium-90 resin microspheres, combined with oxaliplatin-based chemotherapy (OxMdG+SIRT) compared to OxMdG alone in chemotherapy-naïve metastatic colorectal cancer patients with liver metastases (mCRCLM) not suitable for resection/ablation. (Trial number ISRCTN83867919) Self-reported information was collected on primary care resource use, alongside trial-recorded secondary care, treatments, diagnostic tests and Quality of Life (QoL) at baseline and yearly until 5 years. QoL was also collected at 2 months. Costs were calculated employing UK-NHS perspective (2016 £s), and QoL utilities using EQ-5D-3L UK-tariffs. Multiple-imputation was used for missing data and results were adjusted for baseline values. Here we present self-reported resource utilisation and utility; quality-adjusted life years and cost-effectiveness results will be reported subsequently. 364 patients were randomised; median age 63 years, 120/364 (33%) females, and tumour in colon for 261/364 (72%) patients. We limit the time horizon to 3 years, as response rates thereafter fall below 20%. In year 1, total costs (with imputation) were £158.85 in the OxMdG group and £209.44 in OxMdG+SIRT patients, a mean difference (baseline adjusted) of £51.79 (95%CI: -£18.69, £122.27; p=0.15), primarily due to 0.91 additional GP surgery visits (95%CI: 0.05, 1.76; p=0.027). By 3 years, the cumulative difference was not statistically significant (£56.38 (-39.74, 152.5; p=0.24)). The mean difference in utility (with imputation, baseline adjusted) was -0.001 at 2 months (CI95%: -0.05, 0.05), -0.03 at 12 months (-0.16, 0.09), 0.03 at 24 months, (-0.09, 0.16), and -0.03 at 36 months (-0.20, 0.14). Neither complete-case nor unadjusted differences qualitatively changed the results. SIRT did not significantly influence primary care resource use or QoL in the first 3 years. Further analysis of secondary care, treatment and diagnostic test costs is needed to estimate the cost-effectiveness of OxMdG+SIRT.