28564 – NON-BREAST DISEASES MIMICKING BREAST CONDITIONS: A CASE REPORT

Abstract

Introduction: Neoadjuvant chemotherapy (NAC), traditionally used for locally advanced disease, is currently applied to
patients with early breast cancer (BC) of aggressive subtypes (HER-2-positive and triple-negative). BC remains one of the
leading causes of mortality among women worldwide, requiring innovative therapeutic approaches to improve treatment
outcomes. NAC has emerged as a promising strategy, particularly for aggressive breast cancer types, offering the potential
to reduce tumor size before surgery. This study focuses on evaluating pathological complete response (pCR) after NAC
at a public referral center in Brazil, exploring its association with overall survival (OS) and disease-free survival (DFS).
Objectives: This study aims to characterize pCR and its relationship with OS and DFS among BC patients who received
NAC at a Brazilian public referral center, as well as the association between pCR and BC subtypes. Methodology: This
study utilized a retrospective cohort based on Real-World Data (RWD) from a referral center for the treatment of women’s
cancers in Brazil (Hospital Pérola Byington - HPB). Since it involved analysis of the institution’s secondary database, the
present study was approved by the ethics committee. The recommendations of ISPE/ISPOR were followed for the development of an exploratory real-world study. Data from women diagnosed and treated in the referred healthcare setting
between January 2011 and December 2020 were considered for this study. The study was submitted to and approved by
the HPB Research Ethics Committee (approval number: CAAE 39097520.4.2001.0069). Results: Our cohort consisted of
1,601 individuals, of whom 364 (22.7%) achieved pCR (ypT0 ypN0). Patients who achieved pCR showed significantly higher
OS rates (89% vs. 61%, p<0.001) and better DFS (90% vs. 66%, p<0.001), except in the luminal A subtype, in which pCR was
not correlated with improved OS or DFS. Conclusion: Our study demonstrated that data on pCR rates in patients undergoing NAC for BC in real-world settings are consistent with clinical trial data, and that pCR was associated with increases
in OS and DFS in a RWD study. Additionally, it showed that despite limited access to appropriate treatments for HER-2+
and TNBC patients, and given that pCR rates for these subtypes were lower than those reported in randomized clinical
trials, the OS and DFS of patients with pCR were still better.