Early MRI markers of response to neoadjuvant endocrine therapy for patients with hormone receptor-positive/HER2-negative breast cancer

Motivation: Functional tumor volume (FTV) and background parenchymal enhancement (BPE) are potentially useful MRI markers for assessing HR+/HER2- breast cancer undergoing neoadjuvant endocrine treatment (NET). Goal(s): We aimed to investigate the combined ability of FTV and BPE as early markers of treatment response to NET, defined by pre-surgery FTV. Approach: We tested the performance of FTV and BPE available up to 3 weeks of treatment in predicting whether pre-surgery FTV is more than or less than 1.1 cc. Results: Both early changes in FTV and BPE predicted pre-surgery FTV and may be more effective when used in combination. Impact: Functional tumor volume (FTV) and background parenchymal enhancement (BPE) derived from baseline and 3-week MRI predicted the final FTV after neoadjuvant endocrine treatment (NET) for patients with HR+/HER2- breast cancer. These metrics may be non-invasive early markers for NET.