To study the expression of HER2 in high-grade FIGO3 endometrial endometroid carcinoma (EEC) and to correlate our findings with the clinicopathologic characteristics of this tumor. HER2 expression by immunohistochemistry (IHC) was performed on 10% formalin-fixed paraffin embedded tissue on cases diagnosed as FIGO3 EEC. HER2 expression was interpreted as negative (0), low (1+ and 2+) or positive (3+) using similar criteria as in the breast. HER2 amplification by Fluorescence in situ hybridization (FISH) was performed on cases interpreted as 2+ and 3+ by IHC. One hundred and forty-three FIGO3 EEC were identified. Of these, 70 (49%) cases were HER2 negative (IHC 0), and 73 (51%) cases expressed/amplified HER2 by IHC and/or FISH. Of the 73 cases expressing or amplifying HER2, 59 cases were IHC 1+, 12 cases were IHC 2+, and 2 cases were IHC 3+. FISH testing was performed in 12 cases. Only one of the two HER2 IHC 3+ cases showed gene amplification by FISH and the other 11 cases were not amplified. The 5-year overall survival (OS) rate for HER2 IHC 1+ cases was 92.20% (95% CI: 83.97–100.00), and the 5-year OS rate for HER2 IHC 2+/3+ cases was 89.50% (95% CI: 56.41–100.00). Our findings indicate that about one half of FIGO3 EEC variably expresses HER2 and with the emerging concept of “HER2 low”, anti-HER2 agents may be explored as potential therapeutic options in these patients, for possible survival benefits.

中文翻译：

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人表皮生长因子受体2（HER2）在FIGO3高级别子宫内膜子宫内膜样癌中的表达：临床病理特征和未来方向

研究高级别FIGO3子宫内膜癌(EEC)中HER2的表达，并将我们的发现与该肿瘤的临床病理特征相关联。对诊断为FIGO3 EEC 的病例的10% 福尔马林固定石蜡包埋组织进行免疫组织化学 (IHC) 检测 HER2 表达。使用与乳房相似的标准，将 HER2 表达解释为阴性 (0)、低表达（1+ 和 2+）或阳性 (3+)。通过荧光原位杂交 (FISH) 对 IHC 解释为 2+ 和 3+ 的病例进行 HER2 扩增。鉴定出一百四十三个FIGO3 EEC。其中，70 例 (49%) 病例为 HER2 阴性 (IHC 0)，73 例 (51%) 病例通过 IHC 和/或 FISH 表达/扩增 HER2。73例HER2表达或扩增的病例中，59例为IHC 1+，12例为IHC 2+，2例为IHC 3+。12例进行了FISH检测。2例HER2 IHC 3+病例中仅1例FISH显示基因扩增，其余11例未扩增。HER2 IHC 1+ 病例的 5 年总生存 (OS) 率为 92.20% (95% CI: 83.97–100.00)，HER2 IHC 2+/3+ 病例的 5 年 OS 率为 89.50% (95 % CI：56.41–100.00）。我们的研究结果表明，大约一半的 Figo3 EEC 不同程度地表达 HER2，随着“HER2 低”概念的出现，抗 HER2 药物可能被探索作为这些患者的潜在治疗选择，以获得可能的生存益处。