Magnetic resonance imaging before breast cancer surgery: results of an observational multicenter international prospective analysis (MIPA)

Abstract

Objectives: Preoperative breast magnetic resonance imaging (MRI) can inform surgical planning but might cause overtreatment by increasing the mastectomy rate. The Multicenter International Prospective Analysis (MIPA) study investigated this controversial issue.

Methods: This observational study enrolled women aged 18-80 years with biopsy-proven breast cancer, who underwent MRI in addition to conventional imaging (mammography and/or breast ultrasonography) or conventional imaging alone before surgery as routine practice at 27 centers. Exclusion criteria included planned neoadjuvant therapy, pregnancy, personal history of any cancer, and distant metastases.

Results: Of 5896 analyzed patients, 2763 (46.9%) had conventional imaging only (noMRI group), and 3133 (53.1%) underwent MRI that was performed for diagnosis, screening, or unknown purposes in 692/3133 women (22.1%), with preoperative intent in 2441/3133 women (77.9%, MRI group). Patients in the MRI group were younger, had denser breasts, more cancers ≥ 20 mm, and a higher rate of invasive lobular histology than patients who underwent conventional imaging alone (p < 0.001 for all comparisons). Mastectomy was planned based on conventional imaging in 22.4% (MRI group) versus 14.4% (noMRI group) (p < 0.001). The additional planned mastectomy rate in the MRI group was 11.3%. The overall performed first- plus second-line mastectomy rate was 36.3% (MRI group) versus 18.0% (noMRI group) (p < 0.001). In women receiving conserving surgery, MRI group had a significantly lower reoperation rate (8.5% versus 11.7%, p < 0.001).

Conclusions: Clinicians requested breast MRI for women with a higher a priori probability of receiving mastectomy. MRI was associated with 11.3% more mastectomies, and with 3.2% fewer reoperations in the breast conservation subgroup.

Key points: • In 19% of patients of the MIPA study, breast MRI was performed for screening or diagnostic purposes. • The current patient selection to preoperative breast MRI implies an 11% increase in mastectomies, counterbalanced by a 3% reduction of the reoperation rate. • Data from the MIPA study can support discussion in tumor boards when preoperative MRI is under consideration and should be shared with patients to achieve informed decision-making.

Keywords: Breast cancer; Breast-conserving surgery; Magnetic resonance imaging; Mastectomy; Reoperation.

Conflict of interest statement

Outside the present work, the authors declare the following relations with companies and institutions:

Francesco Sardanelli received research grants from – and is a member of the speakers’ bureau of – General Electric Healthcare, Bayer, and Bracco; he is also a member of the Bracco Advisory Group.

Nehmat Houssami receives research funding via a National Breast Cancer Foundation (NBCF Australia) Breast Cancer Research Leadership Fellowship.

Fiona J. Gilbert received research grants from General Electric Healthcare, GSK and Hologic, and had research collaborations with Volpara and Bayer.

Marc B.I. Lobbes received a research grant and is a member of the speakers’ bureau of General Electric Healthcare.

Katja Pinker declares funding by the NIH/NCI Cancer Centre Support Grant P30 CA008748, Digital Hybrid Breast PET/MRI for Enhanced Diagnosis of Breast Cancer (HYPMED), H2020—Research and Innovation Framework Programme PHC-11-2015 # 667211-2, A Body Scan for Cancer Detection using Quantum Technology (CANCERSCAN), H2020-FETOPEN-2018-2019-2020-01 # 828978, Multiparametric 18F-Fluoroestradiol PET/MRI coupled with Radiomics Analysis and Machine Learning for Prediction and Assessment of Response to Neoadjuvant Endocrine Therapy in Patients with Hormone Receptor+/HER2− Invasive Breast Cancer 02.09.2019/31.08.2020 # Nr: 18207, Jubiläumsfonds of the Austrian National Bank.

Simone Schiaffino received travel support from Bracco Imaging and is a member of the speakers’ bureau for General Electric Healthcare.

All other authors declare that they have no conflict of interest related to the present work and that they have nothing to disclose.

© 2021. The Author(s).

Figures

Fig. 1

Study flowchart and results regarding predictors of surgical outcome. For each predictor, odds ratio and 95% confidence interval are reported. R2 represents the Nagelkerke goodness of fit. MRI, magnetic resonance imaging; DM, digital mammography; US, ultrasonography

Fig. 2

Surgical planning and performed surgery in the MRI group. MRI, magnetic resonance imaging

Fig. 3

Reasons for conversion from breast-conserving surgery to mastectomy in the MRI group. MRI, magnetic resonance imaging