A new study from the Netherlands Cancer Institute (IKNL) and the University of Twente indicates that a significant number of breast cancer patients may not be receiving genetic tests that could determine if chemotherapy is necessary. Currently, approximately one in three eligible patients received tests like MammaPrint and Oncotype DX in 2024. These tests analyze tumor genes to predict the risk of cancer recurrence, guiding treatment decisions. While test uptake increased from 9% to 37% after insurance coverage began in 2023, roughly two-thirds of eligible patients still did not receive testing last year, potentially impacting around one thousand women. Data shows patients who tested high-risk were largely treated with chemotherapy (over 80%), while those with low risk rarely received it (under 10%). However, over half of patients eligible for testing but not receiving it underwent chemotherapy, suggesting the lack of test results may lead to overtreatment and exposure to potentially harsh side effects. Researchers are planning further investigation into this issue.