Treatment of HER2+ breast cancer: a retrospective of disease prognosis with loss of HER2 amplification on residual disease after neoadjuvant treatment in a community hospital setting.

Neoadjuvant chemotherapy (NAC) with Anti-Human Epidermal Growth Factor Receptor 2 (Anti-HER2) agents increase rates of pathologic complete response (pCR) in stage II-III, HER2+ breast cancer (BC). Several retrospective studies show HER2 amplification discordance from biopsy to post-NAC residual disease (RD). This phenomenon has unclear prognostic significance. This data was obtained from patients with HER2+ BC treated with NAC between 2018-2021 at our institution. Patients with biopsy and surgical specimens at our institution were analyzed. PCR was defined as ypT0/is N0, and HER2 status on RD was evaluated. 2018 HER2 ASCO/CAP definitions were used. In total, 71 patients were identified. 34/71 patients had pCR and were not included in further analysis. 37/71 patients had RD and HER2 was analyzed. 17/37 had HER2 loss and 20/37 remained HER2 positive. Mean follow-up time for HER2 loss was 43 months and 27 months for patients remaining HER2 positive, but neither group met 5-year Overall Survival as follow-up is ongoing. Recurrence Free Survival (RFS) was 35 months for HER2+ and 43 months for HER2 loss (P = 0.007). However, short follow-up time since diagnosis likely contributed to the underrepresentation of the true RFS of both groups. Therefore, at our institution, retained HER2 positivity on RD after NAC was associated with a statistically worse RFS. Although limited by sample size and follow-up time, further prospective investigation into the significance of HER2 discordance on RD assessed by 2018 definitions could clarify true RFS and if next-generation tumor profiling on RD will yield changes in tailored management.

Association of breast cancer with papillary lesions identified at percutaneous image-guided breast biopsy.

BACKGROUND: The management of papillary lesions identified on image-guided breast biopsy remains controversial. In the literature, data regarding papillary lesions are limited because of small sample sizes. The purpose of this study was to identify the prevalence of atypical ductal hyperplasia and malignancy associated with papillary lesions identified on image-guided breast biopsy. METHODS: This study is a retrospective review of 9,310 consecutive image-guided biopsies performed at our institution between January 1996 and November 2003. Patients were included if they underwent an excisional biopsy after a papillary lesion was diagnosed on image-guided biopsy. RESULTS: Papillary lesions were identified in 153 (2%) of the 9,310 image-guided biopsies performed, and 87 of these patients underwent subsequent excisional biopsy at our institution. Breast cancer (in situ or invasive) was identified in 15 patients (17%), and 16 patients (18%) had atypical ductal hyperplasia identified at excisional biopsy. CONCLUSIONS: These data suggest that excisional biopsy should be considered when a papillary lesion is identified at percutaneous image-guided breast biopsy. The final surgical pathology may impact the treatment plan, risk reduction, and/or surveillance for more than a third of patients diagnosed with a papillary lesion on image-guided biopsy.