Abstract PS1-20: Pathologic lymph lode status of patients with T1 HER2-positive breast cancer who did not receive neoadjuvant chemotherapy using the national cancer database

Abstract

Abstract Purpose: HER2 directed neoadjuvant therapies for locally advanced HER2-positive breast cancer have improved complete pathologic response and event-free survival. For T1 breast cancer, lymph node status often determines whether neoadjuvant treatment is indicated. The aim of this study was to identify patient and tumor characteristics using the National Cancer Database.Methods: A retrospective review of patents diagnosed with T1 clinically node negative (cT1N0) HER2-positive breast cancers was performed using the American College of Surgeons National Cancer Database (ACS NCDB) from 2004-2016. Exclusion criteria included age <18 years and neoadjuvant treatment. Primary outcome was lymph node status. Additional variables included: age, tumor size, tumor location, histology, grade, lymphovascular invasion (LVI), grade, and estrogen receptor (ER) and progesterone receptor (PR) status. Chi-Square tests were performed to evaluate the relationship between these variables and lymph node positive disease. Results: A total of 57,366 T1 HER2-positive patients were identified with 8,994 patients (15.68%) having positive lymph nodes. Characteristics associated with lymph node involvement included age (p<0.001), tumor location (p<0.001), lymphovascular involvement (p<0.001), ER positivity (p=0.021), and PR positivity (p<0.001). There was a significant difference in tumor size when comparing lymph node positive and negative disease (19.06 mm vs. 13.11 mm, p<0.001). Conclusion: Age, tumor location, LVI, ER positivity, PR positivity, and larger tumor size are associated with lymph node involvement in cT1N0 HER2-positive breast cancers. Future research includes determining best practices to identify which patients in this population would benefit from neoadjuvant chemotherapy. Citation Format: Laura DeCesare, Claudia Perez, Neha Nimmagadda, Yanyu Zhang, Samantha Terranella, Nicholas Skertich, Aaron Wiegmann, Andrea Madrigrano, Rosalinda Alvarado, Cristina O'Donoghue. Pathologic lymph lode status of patients with T1 HER2-positive breast cancer who did not receive neoadjuvant chemotherapy using the national cancer database [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-20.