The Future of Quantitative Breast Imaging: Integrated to Integral Imaging Biomarkers for Precision Cancer Care, From the AJR Special Series on Quantitative Imaging

This review explores the potential of quantitative imaging biomarkers (QIBs) for guiding personalized breast cancer treatment through prognostic stratification and measurement of treatment response. Accumulating data from prospective clinical trials show that QIBs are more predictive of treatment outcome than conventional sizebased measures (e.g., change in tumor diameter), highlighting these markers' potential clinical impact. Although QIBs have shown utility in the trial setting, clinical adoption has remained limited. In this article, we present biomarkers derived from dynamic contrast-enhanced MRI, DWI, [18F]FDG PET, and [18F]FES PET, and highlight implementation challenges including variable acquisition protocols, lack of standardization, and uncertainty around optimal timing of imaging during treatment. We distinguish between integrated biomarkers-those used for correlative or exploratory purposes within a trial-and integral biomarkers-those that are essential to trial design and directly inform patient stratification or therapeutic decisions. Standardization efforts by national and international organizations are underway to ensure imaging marker reliability, and commercial tools supporting clinical translation have become available. Dedicated end-to-end solutions remain needed to integrate QIBs into clinical workflows and ultimately into standard care pathways, to promote these markers' role in patient stratification and adaptive treatment decisions.