72P A cost-consequence model assessing gene expression tests among early-stage breast cancer patients in Belgium

In Belgium, early-stage HR+/HER2- breast cancer (BC) patients (pts) may receive adjuvant chemotherapy followed by endocrine treatment to reduce the risk of recurrence. However, chemotherapy does not always lead to improved survival and can be associated with significant healthcare costs, patient burden and treatment-related toxicities. Gene expression tests such as the 21-gene assay (Oncotype DX Breast Recurrence Score® test) can help physicians identify the added clinical benefit of chemotherapy for individual pts and minimise overtreatment. This cost-consequence model aims to analyse the economic impact of employing various gene expression tests versus opting for no testing in Belgium, for pts with early-stage HR+/HER2- BC. A cost-consequence model with a 5-year time horizon was developed to naïvely compare the total costs and frequency of chemotherapy use for three options: Oncotype DX® test, MammaPrint® test and no gene expression testing, separately for pts with N1 (1–3) and without (N0) involved lymph nodes. The model incorporated chemotherapy regimens typical of Belgian clinical practice and was informed by a targeted literature search, as well as publicly available sources, including the Belgian Convention for genomic assay use in BC. Costs for gene expression tests, chemotherapy, administration, short- and long-term adverse events, productivity loss, and recurrence were included. Over a 5-year time horizon,testing with the Oncotype DX test led to total cost savings of €4,940 versus Mammaprint and €18,000 versus not testing per N0 patient. Per N1 patient, savings were €3,388 and €17,928, respectively. Use of the Oncotype DX test resulted in fewer adverse events, sick days and practice visits compared to both alternatives, with most savings made through lower chemotherapy administration costs and productivity losses. Testing with the Oncotype DX test in Belgian clinical practice results in overall cost savings compared to testing with MammaPrint or no testing. These findings highlight the potential for significant economic benefits to the Belgian healthcare system by optimizing chemotherapy treatment for those who most benefit from it.