HER2-low status and response to neoadjuvant chemotherapy in HER2 negative early breast cancer.

PURPOSE: Knowledge on whether low expressions of HER2 have prognostic impact in early-stage breast cancer (BC) and on its response to current chemotherapy protocols can contribute to medical practice and development of new drugs for this subset of patients, changing treatment paradigms. This study aims to evaluate the impact of HER2-low status on response to neoadjuvant chemotherapy (NACT) and survival outcomes in early-stage HER2-negative BC. METHODS: Records from all BC patients treated with NACT from January 2007 to December 2018 in a single cancer center were retrospectively reviewed. HER2-negative (immunohistochemistry [IHC] 0, + 1, or + 2 non-amplified by in situ hybridization [ISH]) patients were included. HER2-low was defined by IHC + 1 or + 2 ISH non-amplified and HER2-0 by IHC 0. The coprimary objectives were to compare pathological complete response (pCR) and relapse-free survival (RFS) between luminal/HER2-low versus luminal/HER2-0 populations and between triple negative (TNBC)/HER2-low versus TNBC/HER2-0. RESULTS: In total, 855 HER2-negative patients were identified. The median follow-up was 59 months. 542 patients had luminal subtype (63.4%) and 313 had TNBC (36.6%). 285 (33.3%) were HER2-low. Among luminal patients, 145 had HER2 IHC + 1 (26.8%) and 91 had IHC + 2/ISH non-amplified (16.8%). In TNBC, 36 had HER2 IHC + 1 (11.5%) and 13 had IHC + 2/ISH non-amplified (4.2%). Most patients had locally advanced tumors, regardless of subtype or HER2-low status. For luminal disease, pCR was achieved in 13% of HER2-low tumors versus 9.5% of HER2-0 (p = 0.27). Similarly, there was no difference in pCR rates among TNBC: 51% versus 47% in HER2-low versus HER2-0, respectively (p = 0.64). HER2-low was also not prognostic for RFS, with 5-year RFS rates of 72.1% versus 71.7% (p = 0.47) for luminal HER2-low/HER2-0, respectively, and 75.6% versus 70.8% (p = 0.23) for TNBC HER2-low/HER2-0. CONCLUSION: Our data does not support HER2-low as a biologically distinct BC subtype, with no prognostic value on survival outcomes and no predictive effect for pCR after conventional NACT.

Benefits of a standardized protocol for axillary management after neoadjuvant chemotherapy in a single center

Introduction: The axillary lymph node status is one of the most important prognostic factors in breast cancer. For locally advanced tumors, neoadjuvant chemotherapy favors higher rates of breast lumpectomy and downstaging tumor burden of axilla. The aim of this study was to evaluate the use of a standardized image-guided protocol after neoadjuvant chemotherapy to enable sentinel node dissection in patients with axillary downstaging, avoiding axillary dissection. Methods: Retrospective cohort study of data collected from medical records of patients who underwent neoadjuvant chemotherapy in a single center, from January 2014 to December 2018. The protocol comprises the placement of a metal clip in positive axillary lymph node, in patients with up to two clinically abnormal lymph nodes presented on imaging. After neoadjuvant chemotherapy, and once a radiologic complete response was achieved, sentinel node dissection was performed using blue dye and radiotracer. Axillary dissection were avoided in patients whose clipped sentinel node were negative for metastasis and in patients with three identified and negative sentinel node dissection. Results: A total of 471 patients were analyzed for this study: 303 before and 165 after the implementation of the protocol; 3 cases were excluded. The rate of sentinel node dissection in clinical nodes positive patients was statistically higher in this group when compared to patients treated before the protocol implementation (22.8% vs. 40.8%; p=0.001). Patients with triple negative and HER2-positive tumors underwent sentinel node dissection more frequently when compared to luminal tumors (p=0.03). After multivariate analysis, the variables that were associated with a greater chance of performing sentinel node dissection were clinical staging, type of surgery performed and implementation of the axillary assessment protocol. Conclusions: The results showed that the use of an easily and accessible image-guided protocol can improve sentinel node dissection in selected patients, even if the lymph node was positive previously to neoadjuvant treatment.