P12: Impact of Margin Status on Local Recurrence in Patients with Breast Cancer Undergoing Breast Conserving Surgery After Neoadjuvant Chemotherapy

Friday, March 24, 2023

12:46 PM – 12:51 PM

Location: SSO HUB: Breast & Endocrine Zone

Poster Presenter(s)

Elise Di Lena, MD (she/her/hers)

General Surgery Resident
McGill University
POINTE-CLAIRE, Quebec, Canada

Disclosure information not submitted.

Author(s)

Elise Di Lena, MD (she/her/hers)

General Surgery Resident
McGill University
POINTE-CLAIRE, Quebec, Canada

Disclosure information not submitted.
EI

Ericka Iny, MD (c)

Medical Student
McGill University, United States

Disclosure information not submitted.
MB

Miranda Bassel, BSc, MSc (c)

Master's in Experimental Surgery Student
McGill University, United States

Disclosure information not submitted.
AS

Arusa Shah, MD (c)

Medical Student
University of Montreal, United States

Disclosure information not submitted.
Stephanie M. Wong, MD MPH

Assistant Professor
McGill Medical School
Montreal, Quebec, Canada

Disclosure information not submitted.
BH

Brent Hopkins, MD, MSc

General Surgery Resident
McGill University, United States

Disclosure information not submitted.
MB

Mark Basik, MD

Breast Surgical Oncologist
Department of Surgery, McGill University Medical School, Montreal, QC, Canada; Department of Oncology, McGill University Medical School, Montreal, QC, Canada, Canada

Disclosure information not submitted.
JB

Jean-Francois Boileau, MD MSc

Surgical Oncologist,Director of the Jewish General Hospital Breast Clinical Trials Group
Associate Professor of Surgery, McGill University, Montreal, QC, Canada; Surgical Oncologist, Segal Cancer Center, Jewish General Hospital, Montreal, Qc, Canada, United States

Disclosure information not submitted.

Poster Presenter(s)

Sarkis Meterissian, MD MSc (he/him/his)

Breast Surgical Oncologist
MUHC Breast Centre, McGill University Medical School
Montreal, Quebec, Canada

Disclosure information not submitted.

Author(s)

Ipshita Prakash, MD, MSc, FRCSC

Assistant Professor of Surgery and Oncology
McGill University, Quebec, Canada

Disclosure information not submitted.

Introduction: Neoadjuvant chemotherapy (NAC) is an increasingly used strategy to downstage breast cancer prior to surgery and to study in vivo tumor response across all tumor sub-types. Questions have been raised as to an increased risk of local recurrence with breast conserving surgery (BCS) post NAC highlighting the uncertainty around optimal margin width in this patient population. We sought to examine the relationship between margin width, number of close margins and in-breast tumor recurrence in this patient population.

Methods: Patients who underwent NAC followed by breast conserving surgery with no ink on tumor for stage I-III breast cancer from 2012 to 2021 were identified within our institutional database. A retrospective chart review was carried out and the Kaplan-Meier method was used to provide estimates for in-breast tumor recurrence and 5-year local recurrence free survival.

Results: A total of 241 patients were included, with a median age of 55 years (IQR 44-65). Biologic tumor subtypes included 30.7% (n=74) with ER+/HER2- disease, 12.5% (n=30) with ER-/HER2+ disease, 22.8% (n=55) with ER+/HER2+ disease, and 34.0% (n=82) with ER-/HER2- disease. Pathologic complete response (pCR) was achieved in 31.1% of patients (n=75). Among patients with residual disease, 15.7% (n=26) had margins < 1 mm (defined as “close”), 84.3% (n=140) had margins ≥1 mm. Of those with close margins, 69.2% (n=18) had only 1 close margin and 30.8% (n=8) had 2 or more. At a median follow-up of 47 months (IQR 24-71), 7.5% of patients had a local recurrence (n=18). The 5-year LRFS was 78.4% (95% CI 44.8-92.9), 87.6% (95% CI 78.3-93.1), and 97.1% (95% CI 81.4-99.6) for patients with close margins, those with ≥1 mm margins, and patients with pCR respectively (p=0.037). There was no difference in local recurrence between the margin categories in those with residual disease (p=0.81) nor was there any impact of the number of close margins (p=0.99).

Conclusions: A margin width of < 1 mm and the number of close margins had no impact on in-breast tumor recurrence or local recurrence free survival rates after NAC in patients with stage I-III breast cancer undergoing breast conserving surgery. Patients with pCR had a higher 5-year LRFS.

Learning Objectives:

Describe the impact of a <1 mm versus a ≥1 mm margin on local recurrence in patients with breast cancer undergoing breast conserving surgery after neoadjuvant chemotherapy.
Question whether additional surgery is necessary in patients with multiple close margins after neoadjuvant chemotherapy.
Understand that patients with breast cancer who have pathologic complete response to neoadjuvant chemotherapy have lower local recurrence rates compared to those with residual disease.