Accuracy of Breast MRI for Surgical Planning After Neoadjuvant Therapy for Patients with Invasive Lobular Carcinoma

Anna Vertido; Tesia McKenzie; Alisha Othieno; Astrid Quirarte; Mandeep Kaur; Mary Kathryn Abel; Maggie Chung; Amie Y Lee; Rita A Mukhtar

doi:10.1245/s10434-025-17735-6

Accuracy of Breast MRI for Surgical Planning After Neoadjuvant Therapy for Patients with Invasive Lobular Carcinoma

Ann Surg Oncol. 2025 Jun 27. doi: 10.1245/s10434-025-17735-6. Online ahead of print.

Authors

Anna Vertido¹, Tesia McKenzie², Alisha Othieno³, Astrid Quirarte¹, Mandeep Kaur⁴, Mary Kathryn Abel⁵, Maggie Chung⁶, Amie Y Lee⁶, Rita A Mukhtar⁷

Affiliations

¹ Division of Surgical Oncology, Department of Surgery, University of California San Francisco, San Francisco, CA, USA.
² Division of Breast Surgery, Riverview Medical Center, Hackensack Meridian Health, Shrewsbury, NJ, USA.
³ Department of Obstetrics and Gynecology, Kaiser Permanente Roseville Medical Center, Roseville, CA, USA.
⁴ School of Medicine, University of California San Francisco, San Francisco, CA, USA.
⁵ Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Massachusetts General Hospital, Boston, MA, USA.
⁶ Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA.
⁷ Division of Surgical Oncology, Department of Surgery, University of California San Francisco, San Francisco, CA, USA. Rita.Mukhtar@ucsf.edu.

PMID: 40576899
DOI: 10.1245/s10434-025-17735-6

Abstract

Background: Invasive lobular carcinoma (ILC) is the second most common subtype of breast cancer, comprising 10-15% of cases. Due to its diffuse growth pattern, conventional imaging techniques have decreased sensitivity for ILC. While breast magnetic resonance imaging (MRI) is often recommended for ILC, its accuracy following neoadjuvant therapy is unknown. We evaluated the accuracy of post-treatment MRI and examined the impact on surgical outcomes.

Patients and methods: We retrospectively analyzed 129 patients with ILC who underwent neoadjuvant chemotherapy (NAC) or endocrine therapy (NET) and had post-treatment MRI. We considered a 0.5 cm difference between longest tumor diameter on MRI and pathologic tumor size to be discrepant. Tumor imaging phenotype was categorized as mass, non-mass enhancement (NME), or mass + NME. We evaluated concordance between imaging and pathology by tumor phenotype and associations with positive margin rates using Stata 18.0.

Results: Post-treatment MRI underestimated tumor size in 52.5% of cases, was concordant in 25.3%, and overestimated in 22.2%. The presence of NME was associated with a higher rate of tumor size underestimation (62.5% versus 39.5% for mass only, p = 0.023); mean underestimation was 3.4 cm in those with NME. Underestimation was associated with higher positive margin rates following breast-conserving surgery (p = 0.018). Finally, among patients with complete imaging response on MRI, 93.3% had residual invasive disease on pathology.

Conclusions: Following neoadjuvant therapy, post-treatment MRI frequently underestimates tumor size in ILC, particularly in tumors with NME. Surgeons should consider these imaging limitations when planning resection, which could improve surgical outcomes.