Emerging imaging biomarkers in breast cancer: transforming screening, staging, and therapeutic assessment

In patients with early-stage breast cancer, a pathological complete response (pCR) after neoadjuvant chemotherapy is linked to a better prognosis. The increasing number of postneoadjuvant treatment approaches that have shown potential in the absence of pCR has led to an increase in the search for predictive biomarkers of response and the use of neoadjuvant systemic therapy in patients with early breast cancer. Better response prediction to neoadjuvant chemotherapy may help with the escalation or de-escalation of neoadjuvant treatment approaches, ultimately leading to better clinical management of early breast cancer. Clinico-pathological prognostic factors are now used to evaluate the potential benefit of neoadjuvant systemic treatment; however, their accuracy is not high enough to allow for tailored response prediction. Because breast cancer exhibits intertumoral heterogeneity, other recently proposed criteria are either not yet relevant in ordinary clinical practice or are somewhat very helpful. This book chapter concentrates on the numerous gene signatures that have recently been suggested for patient stratification and treatment response prediction, in addition to the existing biomarkers utilized for clinical decision-making. In this study, we outline the current understanding of the characteristics that predict a patient’s response to neoadjuvant chemotherapy for breast cancer and emphasize potential future developments that might improve response prediction. We also discuss intratumoral phenotypic heterogeneity in breast cancers, relevant preclinical models, and potential novel approaches that include this biological factor currently limiting response prediction accuracy to neoadjuvant systemic therapy.