HER2 Testing Characteristics Can Predict Residual Cancer Burden following Neoadjuvant Chemotherapy in HER2-Positive Breast Cancer

International Journal of Breast Cancer

Barbara Susnik¹  Mara Rendi¹  Tamera J. Lillemoe¹  Erin Grimm¹  Susan Olet²  Janet Krueger³  Monica Knaack³  Rina Yarosh³  Michaela L. Tsai³  Karen K. Swenson³ 

[1] Allina Health Laboratory-Hospital Pathology Associates, 800 East 28th Street, Minneapolis, MN 55407, USA;Allina Health System, Research Informatics, 925 Chicago Avenue, Minneapolis, MN 55407, USA;Allina Health System, Virginia Piper Cancer Institute Clinical Research Program, 800 East 28th Street, Minneapolis, MN 55407, USA;

DOI  :  10.1155/2021/6684629

来源: Hindawi Publishing Corporation

【 摘 要 】

Objectives. The response to HER2-targeted neoadjuvant chemotherapy (NAC) in HER2-positive (+) breast cancer can be quantified using residual cancer burden (RCB) pathologic evaluation to predict relapse free/overall survival. However, more information is needed to characterize the relationship between patterns of HER2 testing results and response to NAC. We evaluated clinicopathologic characteristics associated with RCB categories in HER2+ patients who underwent HER2-directed NAC. Methods. A retrospective chart review was conducted with Stage I–III HER2+ breast cancer cases following NAC and surgical resection. HER2 immunohistochemistry (IHC) staining and fluorescence in situ hybridization (FISH), histologic/clinical characteristics, hormone receptor status, and RCB scores (RCB-0, RCB-I, RCB-II, and RCB-III) were evaluated. Results. 64/151 (42.4%) patients with HER2+ disease had pathologic complete response (pCR). Tumors with suboptimal response (RCB-II and RCB-III) were more likely to demonstrate less than 100% HER2 IHC 3+ staining (p<0.0001), lower HER2 FISH copies (p<0.0001), and lower HER2/CEP17 ratios (p=0.0015) compared to RCB-I and RCB-II responses. Estrogen receptor classification using ≥10% versus ≥1% staining showed greater association with higher RCB categories. Conclusions. HER2+ characteristics show differing response to therapy despite all being categorized as positive; tumors with less than 100% IHC 3+ staining, lower HER2 FISH copies, and lower HER2/CEP17 ratios resulted in higher RCB scores.

【 授权许可】

CC BY