Multiparametric MR imaging to assess response following neoadjuvant systemic treatment in various breast cancer subtypes: Comparison between different definitions of pathologic complete response

• Published in: European journal of radiology 2019-08, Vol.117, p.132-139
• Main Authors: Santamaría, G, Bargalló, X, Ganau, S, Alonso, I, Muñoz, M, Mollà, M, Fernández, PL, Prat, A
• Format: Article
• Language: English
• Subjects: Breast cancer; Diffusion weighted MRI; Magnetic resonance imaging; Neoadjuvant treatment
• ISSN: 0720-048X; 1872-7727
• DOI: 10.1016/j.ejrad.2019.06.009

To validate the performance of multiparametric magnetic resonance (MR) imaging to assess pathologic response to neoadjuvant systemic therapy (NST) in various breast cancer subtypes considering two definitions of pCR: absence of any residual invasive cancer or DCIS (ypT0) and absence of invasive tumour cells (ypT0/is). Institutional review board–approved retrospective study, with waiver of the need to obtain informed consent. From January 2015 to June 2017, 81 women with 82 breast cancers undergoing NST were included. Eighteen lesions (22%) were immunohistochemically HER2-positive, 12 (15%) triple negative (TN), 42 (51%) luminal B-like and 10 (12%) luminal B-like/HER2-positive. Breast MR imaging was performed before and after NST. A comparative analysis considering pCR as ypT0 and ypT0/is was carried out. Performance of univariate and multivariate models to potentially predict pathologic response were evaluated. ypT0 was attained in 23% (19/82) of cases and ypT0/is in 33% (27/82) of cases. In both scenarios, HER2-positive subtype achieved the best response, 53% and 48%, respectively. A significant relationship was found between late enhancement and pathologic response (p