13: Luminal A vs B After Choosing Wisely: Do Phenotypes Affect Oncologic Outcomes?

Saturday, March 25, 2023

8:11 AM – 8:22 AM

Location: Veterans Memorial Auditorium

Abstract Presenter(s)

Cynthia Ong (she/her/hers)

Medical Student
Virginia Commonwealth University School of Medicine
Midlothian, Virginia, United States

Disclosure(s): No financial relationships to disclose

First Author(s)

Cynthia Ong (she/her/hers)

Medical Student
Virginia Commonwealth University School of Medicine
Midlothian, Virginia, United States

Disclosure(s): No financial relationships to disclose

Author(s)

Christian Blue, MS

Medical Student
Virginia Commonwealth University School of Medicine
Richmond, Virginia, United States

Disclosure information not submitted.
JK

Jamal Khan, MS

Medical Student
Virginia Commonwealth University School of Medicine, United States

Disclosure information not submitted.
XD

Xiaoyan Deng, MS

Senior Biostatistician
Virginia Commonwealth University Department of Biostatistics, United States

Disclosure information not submitted.
RL

Raphael Louie, MD MPH

Assistant Professor of Surgery
Virginia Commonwealth University, Department of Surgery, United States

Disclosure information not submitted.
Kandace P. McGuire, MD, FACS

Professor of Surgery
Virginia Commonwealth University
Richmond, Virginia, United States

Disclosure information not submitted.

Disclosure(s):

Cynthia Ong: No financial relationships to disclose

Introduction: In 2016, the Choosing Wisely campaign recommended the omission of sentinel lymph node biopsy (SLNB) in women ≥70 years old diagnosed with early-stage hormone receptor positive (HR+), HER2 negative (HER2-) breast cancer. While studies have shown that SLNB can be safely omitted in HR+ breast cancer, no distinction is made between luminal A and luminal B disease phenotypes. This study aims to evaluate the effect of SLNB on oncologic outcomes in HER2- luminal B compared to luminal A breast cancer.

Methods: We performed an IRB-approved, single institution, retrospective cohort study from 2010-2020 of women age ≥70 with clinically node negative, HR+ breast cancer undergoing definitive surgical treatment. Our primary endpoints were locoregional recurrence (LRR), disease free survival (DFS), and overall survival (OS). Patients were stratified by luminal type according to gene expression panel testing, Ki67, and/or pathologic grading. Statistical analysis using univariate and multivariate analyses were used to assess the primary endpoints.

Results: Of the 383 patients identified, 310 patients underwent SLNB vs 73 who did not. 286 patients were luminal A and 97 were luminal B. When comparing patient demographics (mean age, tumor staging, overall grade, and treatment), there was no statistical difference between the two groups. SLNB did not have a significant difference in LRR in either luminal A (p=0.92) or luminal B (p=0.96) disease. SLNB had an improved DFS (p < 0.05) and OS (p < 0.01) in Luminal A disease, but was statistically insignificant in DFS (p=0.73) and OS (p = 0.36) in luminal B disease. On multivariate analysis, increasing age (HR=1.17; p< 0.01) and tumor size (HR = 1.03; p< 0.05) were associated with DFS, while SLNB was not (p=0.71). Luminal status (HR=0.52, p< 0.05), increasing age (HR=1.15, p< 0.01), and comorbidities (HR=1.35, p< 0.05) were associated with OS, while SLNB was not (p=0.71).

Conclusions: Despite phenotypic differences, our results suggest SLNB may be safely omitted in patients over the age of 70 with Luminal B disease with similar locoregional recurrence in Luminal A disease. Our findings suggest DFS and OS may be driven by tumor biology, patient age, and comorbidities rather than receipt of SLNB. Additional studies may look at the value of SLNB in other subtypes, including HER2 positive disease and triple negative disease.
Learning Objectives:
Describe the impact of sentinel lymph node biopsy on oncologic outcomes between luminal A and luminal B breast tumor subtypes.
Describe proper implementation of sentinel lymph node biopsy based on pathology in clinically node negative patients 70 years or older.
Demonstrate a more precise understanding of the 2016 Society of Surgical Oncology’s Choosing Wisely Guidelines regarding sentinel lymph node biopsy in patients 70 or older.