Abstract：
BACKGROUND: Approximately, 55% of breast carcinomas are reported to be HER-2 low breast carcinomas. Trastuzumab-Deruxtecan is a new FDA-approved targeted therapy for HER-2 low metastatic breast carcinomas, making it essential that all efforts are made to identify these tumors in specimens submitted for pathologic examination. Cytology specimens are often the first and only modality of this assessment due to the ease of specimen procurement. This study aimed to determine the variability in HER-2 immunostaining interpretation among observers using cytologic specimens from metastatic sites.
METHODS: A pathology database search was made to identify metastatic breast carcinoma reported in cytology specimens. A manual search was then done to identify cases of HER-2 low category, H&E cell block and HER-2 neu immunostain slides were retrieved for a total of 50 cases. Reviewer #1 and #2 independently interpreted HER-2 immunostain of all 50 cases. Only discordant cases were sent for reviewer-3 interpretation. All three were blinded by the metastatic site, and original HER-2 interpretation.
RESULTS: Of 50 cases, 11 cases (22%) were reported as concordant scores between reviewer #1 and reviewer #2 but had a discordant original IHC report. Additionally, 4 cases (8%) had discordant reporting of HER2 IHC stain between reviewer #1 and reviewer #2 making a total of 15 cases (30%) with overall discordant results.
CONCLUSIONS: This study highlights the interobserver variability of HER-2 immunostain interpretation for HER-2 low category of breast carcinomas. We recommend the need for more robust laboratory techniques including molecular for uniform identification of these unique targetable metastatic breast carcinoma groups.
METHODS: A pathology database search was made to identify metastatic breast carcinoma reported in cytology specimens. A manual search was then done to identify cases of HER-2 low category, H&E cell block and HER-2 neu immunostain slides were retrieved for a total of 50 cases. Reviewer #1 and #2 independently interpreted HER-2 immunostain of all 50 cases. Only discordant cases were sent for reviewer-3 interpretation. All three were blinded by the metastatic site, and original HER-2 interpretation.
RESULTS: Of 50 cases, 11 cases (22%) were reported as concordant scores between reviewer #1 and reviewer #2 but had a discordant original IHC report. Additionally, 4 cases (8%) had discordant reporting of HER2 IHC stain between reviewer #1 and reviewer #2 making a total of 15 cases (30%) with overall discordant results.
CONCLUSIONS: This study highlights the interobserver variability of HER-2 immunostain interpretation for HER-2 low category of breast carcinomas. We recommend the need for more robust laboratory techniques including molecular for uniform identification of these unique targetable metastatic breast carcinoma groups.
摘要：
背景：大约，据报道，55％的乳腺癌是HER-2低乳腺癌。曲妥珠单抗-Deruxtecan是一种新的FDA批准的靶向治疗HER-2低转移性乳腺癌，因此，必须尽一切努力在提交病理检查的标本中识别这些肿瘤。由于标本采购的便利性，细胞学标本通常是此评估的第一个也是唯一的方式。这项研究旨在使用转移部位的细胞学标本确定观察者之间HER-2免疫染色解释的变异性。
方法：进行病理数据库检索，以确定在细胞学标本中报告的转移性乳腺癌。然后进行手动搜索以识别HER-2低类别的病例，共检索了50例H&E细胞块和HER-2neu免疫染色载玻片。1号和2号审稿人独立解释所有50例的HER-2免疫染色。只有不和谐的病例被送交审核员-3解释。这三个人都被转移部位蒙蔽了眼睛，和原始的HER-2解释。
结果：50例，11例（22％）报告为1号审阅者和2号审阅者之间的一致评分，但原始IHC报告不一致。此外,4例（8％）在1号审阅者和2号审阅者之间的HER2IHC染色报告不一致，总共15例（30％），总体结果不一致。
结论：本研究强调了HER-2低类型乳腺癌的HER-2免疫染色解释的观察者间差异。我们建议需要更强大的实验室技术，包括用于统一鉴定这些独特的可靶向转移性乳腺癌组的分子。
方法：进行病理数据库检索，以确定在细胞学标本中报告的转移性乳腺癌。然后进行手动搜索以识别HER-2低类别的病例，共检索了50例H&E细胞块和HER-2neu免疫染色载玻片。1号和2号审稿人独立解释所有50例的HER-2免疫染色。只有不和谐的病例被送交审核员-3解释。这三个人都被转移部位蒙蔽了眼睛，和原始的HER-2解释。
结果：50例，11例（22％）报告为1号审阅者和2号审阅者之间的一致评分，但原始IHC报告不一致。此外,4例（8％）在1号审阅者和2号审阅者之间的HER2IHC染色报告不一致，总共15例（30％），总体结果不一致。
结论：本研究强调了HER-2低类型乳腺癌的HER-2免疫染色解释的观察者间差异。我们建议需要更强大的实验室技术，包括用于统一鉴定这些独特的可靶向转移性乳腺癌组的分子。
