Clinicopathologic characteristics of HER2-positive metaplastic squamous cell carcinoma of the breast

• Published in: Journal of clinical pathology Vol. 75; no. 1; p. 18
• Main Authors: Lei, Ting, Pu, Tianjie, Wei, Bing, Fan, Yingying, Yang, Libo, Shen, Mengjia, Chen, Min, Yang, Jieliang, Zhang, Yu, Zhang, Zhang, Bu, Hong
• Format: Journal Article
• Language: English
• Published: England 01-01-2022
• Subjects: Adult; Aged; Breast - pathology; Breast Neoplasms - classification; Breast Neoplasms - diagnosis; Breast Neoplasms - pathology; Carcinoma, Squamous Cell - classification; Carcinoma, Squamous Cell - diagnosis; Carcinoma, Squamous Cell - pathology; China; Disease-Free Survival; Female; Humans; Immunohistochemistry; In Situ Hybridization, Fluorescence; Middle Aged; Prognosis; Receptor, ErbB-2 - genetics; Receptor, ErbB-2 - metabolism; China; breast cancer; cancer research; breast pathology
• ISSN: 1472-4146
• DOI: 10.1136/jclinpath-2020-206468

The aim of this study was to analyse the clinicopathological features and prognosis of human epidermal growth factor receptor-2 (HER2)-positive metaplastic squamous cell carcinoma (MSCC).
Fifty-eight patients with MSCC of the breast who were classified into 45 triple-negative and 13 HER2-positive subgroups diagnosed at the West China Hospital, Sichuan University, from 2004 to 2018, were enrolled. Clinicopathological features were collected and compared between HER2-positive MSCC, triple-negative MSCC, HER2-positive invasive breast carcinoma of no special type (NST) and triple-negative NST groups. In the prognostic survival analysis, HER2-positive MSCCs was compared with triple-negative MSCCs, HER2-positive NSTs and triple-negative NSTs.
Compared with triple-negative MSCCs, more patients with Ki-67 low expression were in HER2-positive MSCCs (p<0.05). More patients with HER2-positive MSCC than patients with HER2-positive NST were postmenopausal (p<0.05). Compared among HER2-positive MSCCs, triple-negative MSCCs and triple-negative NSTs, patients of HER2-positive MSCCs with high Ki-67 expression were the least, and HER2-positive MSCCs had more strongly associated with postmenopausal disease status (p<0.05). In survival analyses, HER2-positive MSCCs had a high risk of recurrence and poor prognosis (p<0.05). Lymph node status was significantly associated with the disease-free survival of patients with HER2-positive MSCC.
In conclusion, our study indicates that HER2-positive MSCC is an aggressive disease with unique clinicopathological characteristics. Both HER2-positive status and an SCC component are critical factors for poor prognosis. HER2-positive MSCC and triple-negative MSCC are distinct subgroups. Corresponding targeted therapy recommendations should be made for this HER2-positive MSCC group.