E9: Impact of Close Margins in Breast Conserving Surgery Following Neoadjuvant Chemotherapy

ePoster Abstract Author(s)

Alexa C. Glencer, MD

Fellow
Department of Breast Surgical Oncology, MD Anderson Cancer Center Houston TX, U.S.A.
Houston, Texas, United States

Submitter(s)

Alexa C. Glencer, MD

Fellow
Department of Breast Surgical Oncology, MD Anderson Cancer Center Houston TX, U.S.A.
Houston, Texas, United States

Author(s)

Alexa C. Glencer, MD

Fellow
Department of Breast Surgical Oncology, MD Anderson Cancer Center Houston TX, U.S.A.
Houston, Texas, United States
MY

Min Yi, M.D., PhD

Biostatistician
Department of Breast Surgical Oncology, MD Anderson Cancer Center, Houston TX, U.S.A., United States
HW

Hannah Wingate, PhD

Associate Professor, Chair Department of Biology, Biochemistry & Molecular Biology
Houston Christian University, Houston TX, U.S.A., United States
NA

Naid Allassan, PA-C

Physician Assistant
Department of Breast Surgical Oncology, MD Anderson Cancer Center, Houston TX, U.S.A., United States
SA

Sarah Alameddine, n/a

Student Researcher
Department of Breast Surgical Oncology, MD Anderson Cancer Center, Houston TX, U.S.A., United States
Kelly K. Hunt, MD (she/her/hers)

Professor & Chair
Department of Breast Surgical Oncology, MD Anderson Cancer Center, Houston, TX, USA
Houston, Texas, United States
Ana P. Refinetti, M.D.

Associate Professor
Department of Breast Surgical Oncology, MD Anderson Cancer Center, Houston TX, U.S.A.
Houston, TX, United States

Introduction: Limited data have informed our practice standard of “no ink on tumor” as a sufficient margin for breast conserving surgery (BCS) following neoadjuvant chemotherapy (NAC). This study sought to determine if wider margins were associated with improved locoregional recurrence (LRR) and survival in patients treated with NAC and BCS.

Methods: Patients treated with NAC and BCS for stage I-III invasive breast cancer from 1999 to 2015 at a single institution were identified from a prospectively maintained database. Patients were divided into three groups based on closest surgical margin (≤1mm, 1-2mm, ≥2mm). LRR-free survival (LRRFS), disease-specific survival (DSS), and overall survival (OS) were compared among the groups with a multivariate Cox proportional hazards model used to identify clinical and pathologic features associated with each outcome.

Results: 779 patients were included. Median follow up was 6.9 years. Median age was 52 (range 26-84) years with 327 (42.0%) patients premenopausal and 440 (56.5%) postmenopausal. Tumor size was T1 in 121 (15.5%) patients, T2 in 612 (78.6%), and T3/T4 in 46 (5.9%). Pathologic N stage was N0 in 690 (88.6%) patients, N1 in 79 (10.1%), and N2/N3 in 10 (1.3%). Receptor subtypes included 246 (32%) HR-/HER2-, 59 (7.7%) HR-/HER2+, 341 (44.4%) HR+/HER2-, and 122 (15.9%) HR+/HER2+. Final margins were ≤1mm in 94 (12.1%), 1-2mm in 229 (29.4%), and ≥2mm in 456 (58.5%) patients. The 5-year LRRFS was 98.6% for margins ≤1mm, 97.9% for 1-2mm, and 96.4% for margins ≥2mm. The 5-year DSS was 98.4% for margins ≤1mm, 98.1% for 1-2mm, and 95.0% for margins ≥2mm. The 5-year OS was 97.2% for margins ≤1mm, 97.3% for 1-2mm, and 91.1% for margins ≥2mm. On multivariate analysis, there was no significant difference in LRRFS, DSS, or OS comparing margins ≤1mm vs 1-2mm vs ≥2mm. HR-/HER2+ tumor subtype was associated with worse LRRFS (p=0.03) and triple negative subtype with worse OS (p=0.03). Pathologic node negativity (p<0.0001), receipt of radiation therapy (p=0.005), and receipt of endocrine therapy (p=0.002) were each associated with improved DSS. More advanced N stage was associated with worse DSS (N1 vs N0, HR=3.9, p< 0.0001; N2/3 vs N0, HR=12.2, p< 0.0001) and OS (N1 vs N0, HR=2.1, p=0.007; N2/3 vs N0, HR=3.9, p=0.01).

Conclusions: In this large cohort of patients undergoing BCS following NAC, there was no association between margin width of ≤1mm vs 1-2mm vs ≥2mm and LRFS, DSS, or OS. This study supports the continued practice of “no ink on tumor” as a sufficient margin in these patients.

Learning Objectives:

Determine if locoregional breast cancer recurrence is impacted by close surgical margins, defined as less than 1mm or 1-2mm, at breast conserving surgery in patients who have received neoadjuvant chemotherapy.
Determine if breast cancer-specific survival is impacted by close surgical margins, defined as less than 1mm or 1-2mm, at breast conserving surgery in patients who have received neoadjuvant chemotherapy.
Identify clinical and pathologic features that impact locoregional breast cancer recurrence or survival in patients who have received neoadjuvant chemotherapy and breast conserving surgery.