A Five-Year Retrospective Analysis of Neoadjuvant Therapy in Early-Stage Breast Cancer: Subtype Outcomes and Imaging Concordance

Abstract

Although neoadjuvant systemic treatment (NST) is well established in the management of early breast cancer, there are limited clinical data available beyond the highly selected population evaluated in clinical trials. In this study, we assessed real-world outcomes of NST in early breast cancer through a retrospective review of 201 patients treated between November 2019 and February 2025. Pathological complete response (pCR) rates were highest in HER2-positive (60.2%) and triple-negative (53.1%) breast cancer subtypes and lowest in those who were identified as oestrogen receptor-positive (ER-positive)/HER2-negative (11.1%). In HER2-positive disease, pCRs were more frequent in ER-negative (75.8%) than ER-positive (50.0%) cases, while pCR rates in triple-negative breast cancer were similar with and without immunotherapy. Baseline positron emission tomography/computed tomography (PET/CT) upstaged 37% (35/94) of patients and showed 87% concordance with pathology, whereas magnetic resonance imaging (MRI) demonstrated a false-negative rate of 17% and a false-positive rate of 1.1%. In these cases, MRI results suggested residual disease despite a complete pathological response, with discrepancies varying by tumour subtype. Forty-two percent of the patients underwent chemotherapy dose reductions; 12% required hospitalisation. NST was effective across aggressive subtypes, with pCR rates comparable to those observed in clinical trials. In summary, our results highlighted the contributions of functional imaging with PET/CT and MRI to staging, treatment response assessments and surgical planning in real-world clinical practice.