Abstract 11P
Background
In HER2-positive early breast cancer patients who underwent neoadjuvant chemotherapy (NAC), pathologic complete response (pCR) has been shown to be a favorable prognostic factor. However, prognostic factors for non-pCR patients are unclear. In this study, we analyzed prognostic factors in non-pCR patients.
Methods
A prospective database of 165 clinical stage I to Ⅲ, HER2-positive breast cancer patients who underwent NAC from January 2009 to January 2024 was analyzed. HER2 was evaluated using fluorescence in situ hybridization assay (FISH) or immunohistochemistry (IHC). Patients were included if they were FISH≧2.0 or IHC score of 3+.
Results
Median age, tumor size of the entire 165 patients was 56.0 years (range=22.0-85.0), 3.0 cm (range=0.4-12.0 cm), respectively. 60 (36.4%) patients had lymph node metastasis. 101 (61.2%) patients revealed hormone receptor positive [estrogen receptor positive: 98 patients, progesterone receptor (PgR) positive: 67 patients]. All patients received NAC consisting of trastuzumab and docetaxel or paclitaxel. 29 (33.0%) patients received trastuzumab with pertuzumab, 34 (38.6%) patients received taxane followed by anthracycline. Among all patients, 88 (53.3%) patients had not achieved pCR. Among non-pCR patients, HER2 status has turned to negative in 31 (35.2%) patients (HER2-loss) and 57 (64.8%) patients maintained HER2-positive status (HER2-positive) in surgical specimens. Patients with low nuclear grade (NG) and PgR positive had a significantly higher rate of HER2-loss compared to patients with high NG [NG1 vs. NG2 and 3; 16 (59.3%) patients vs. 15 (25.0%) patients, p=0.003] and PgR negative [PgR positive vs. negative; 23 (46.0%) patients vs. 8 (21.1%) patients], respectively. With a median follow-up time of 56.7 months, disease-free survival (DFS) was significantly better in HER2-loss patients than in HER2-positive patients (95.2% vs 76.0%, p=0.041). Univariate analyses showed that hormone receptor status, HER2 loss and use of pertuzumab were related factors for DFS. However, no independent associated factors for DFS were found in the multivariate analysis.
Conclusions
The findings of this study suggested that HER2 change after NAC might be associated with a prognosis.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Department of Surgery, Teikyo University School of Medicine.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.