Screening and diagnostic breast MRI: how do they impact surgical treatment? Insights from the MIPA study
Authors: Cozzi Andrea , Di Leo Giovanni , Houssami Nehmat , Gilbert Fiona J. , Helbich Thomas H. , Álvarez Benito Marina , Balleyguier Corinne , Bazzocchi Massimo , Bult Peter , Calabrese Massimo , Camps Herrero Julia , Cartia Francesco , Cassano Enrico , Clauser Paola , de Lima Docema Marcos F. , Depretto Catherine , Dominelli Valeria , Forrai Gábor , Girometti Rossano , Harms Steven E. , Hilborne Sarah , Ienzi Raffaele , Lobbes Marc B. I. , Losio Claudio , Mann Ritse M. , Montemezzi Stefania , Obdeijn Inge-Marie , Ozcan Umit A. , Pediconi Federica , Pinker Katja , Preibsch Heike , Raya Povedano José L. , Rossi Saccarelli Carolina , Sacchetto Daniela , Scaperrotta Gianfranco P. , Schlooz Margrethe , Szabó Botond K. , Taylor Donna B. , Ulus Özden S. , Van Goethem Mireille , Veltman Jeroen , Weigel Stefanie , Wenkel Evelyn , Zuiani Chiara , Sardanelli Francesco 
Published: May 2023

Abstract
Objectives
To report mastectomy and reoperation rates in women who had breast MRI for screening (S-MRI subgroup) or diagnostic (D-MRI subgroup) purposes, using multivariable analysis for investigating the role of MRI referral/nonreferral and other covariates in driving surgical outcomes.

Methods
The MIPA observational study enrolled women aged 18–80 years with newly diagnosed breast cancer destined to have surgery as the primary treatment, in 27 centres worldwide. Mastectomy and reoperation rates were compared using non-parametric tests and multivariable analysis.

Results
A total of 5828 patients entered analysis, 2763 (47.4%) did not undergo MRI (noMRI subgroup) and 3065 underwent MRI (52.6%); of the latter, 2441/3065 (79.7%) underwent MRI with preoperative intent (P-MRI subgroup), 510/3065 (16.6%) D-MRI, and 114/3065 S-MRI (3.7%). The reoperation rate was 10.5% for S-MRI, 8.2% for D-MRI, and 8.5% for P-MRI, while it was 11.7% for noMRI (p ≤ 0.023 for comparisons with D-MRI and P-MRI). The overall mastectomy rate (first-line mastectomy plus conversions from conserving surgery to mastectomy) was 39.5% for S-MRI, 36.2% for P-MRI, 24.1% for D-MRI, and 18.0% for noMRI. At multivariable analysis, using noMRI as reference, the odds ratios for overall mastectomy were 2.4 (p < 0.001) for S-MRI, 1.0 (p = 0.957) for D-MRI, and 1.9 (p < 0.001) for P-MRI.

Conclusions
Patients from the D-MRI subgroup had the lowest overall mastectomy rate (24.1%) among MRI subgroups and the lowest reoperation rate (8.2%) together with P-MRI (8.5%). This analysis offers an insight into how the initial indication for MRI affects the subsequent surgical treatment of breast cancer.

Key Points
• Of 3065 breast MRI examinations, 79.7% were performed with preoperative intent (P-MRI), 16.6% were diagnostic (D-MRI), and 3.7% were screening (S-MRI) examinations.
• The D-MRI subgroup had the lowest mastectomy rate (24.1%) among MRI subgroups and the lowest reoperation rate (8.2%) together with P-MRI (8.5%).
• The S-MRI subgroup had the highest mastectomy rate (39.5%) which aligns with higher-than-average risk in this subgroup, with a reoperation rate (10.5%) not significantly different to that of all other subgroups.