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Abstract：
OBJECTIVE: The updated 2013 American Society of Clinical Oncology/College of American Pathologists guideline recommendations for human epidermal growth factor receptor 2 (HER2) testing have made some major changes in HER2 fluorescence in situ hybridization (FISH) interpretation criteria with additional FISH equivocal cases. Repeat HER2 testing is recommended after initial HER2 FISH equivocal results; however, little is known about its impact on final HER2 status. The aim of this study is to investigate whether reflex test clarifies HER2 status, and to characterize clinicopathological features of the newly defined HER2 equivocal group.
METHODS: A total of 886 consecutive cases of primary invasive breast cancer conducted with dual-probe HER2 FISH testing between November 2013 and December 2015 were reviewed. HER2 immunohistochemistry (IHC) and FISH testing were performed on a different tissue block or a new specimen after initial HER2 FISH equivocal results.
RESULTS: Compared to 2007 guideline, 85 (9.6%) cases changed their category by using 2013 guideline. The major change of the 85 cases is that 57 (6.4%) cases in HER2 FISH-negative category changed to equivocal, and the equivocal category cases increased from 36 to 67. HER2 FISH equivocal was significantly associated with HER2 IHC equivocal (2+) and chromosome 17 polysomy (P < 0.01). Repeat testing by IHC and FISH clarified HER2 status in 33 and 42% of HER2 equivocal cases, respectively. Overall 32 (48%) initial HER2 equivocal cases stayed HER2 equivocal after repeat FISH and or IHC testing. These tumors were ER/PR+, with high KI-67 index.
CONCLUSIONS: New guidelines classify more HER2 FISH equivocal cases. Repeat HER2 testing clarifies HER2 status in about 50% of initial HER2 FISH equivocal cases. In addition, HER2 equivocal cases merit further study as there is limited information about prognosis and optimal treatment strategy for this population.
METHODS: A total of 886 consecutive cases of primary invasive breast cancer conducted with dual-probe HER2 FISH testing between November 2013 and December 2015 were reviewed. HER2 immunohistochemistry (IHC) and FISH testing were performed on a different tissue block or a new specimen after initial HER2 FISH equivocal results.
RESULTS: Compared to 2007 guideline, 85 (9.6%) cases changed their category by using 2013 guideline. The major change of the 85 cases is that 57 (6.4%) cases in HER2 FISH-negative category changed to equivocal, and the equivocal category cases increased from 36 to 67. HER2 FISH equivocal was significantly associated with HER2 IHC equivocal (2+) and chromosome 17 polysomy (P < 0.01). Repeat testing by IHC and FISH clarified HER2 status in 33 and 42% of HER2 equivocal cases, respectively. Overall 32 (48%) initial HER2 equivocal cases stayed HER2 equivocal after repeat FISH and or IHC testing. These tumors were ER/PR+, with high KI-67 index.
CONCLUSIONS: New guidelines classify more HER2 FISH equivocal cases. Repeat HER2 testing clarifies HER2 status in about 50% of initial HER2 FISH equivocal cases. In addition, HER2 equivocal cases merit further study as there is limited information about prognosis and optimal treatment strategy for this population.
摘要：
目的：更新的2013年美国临床肿瘤学会/美国病理学家学会关于人类表皮生长因子受体2（HER2）测试的指南建议在HER2荧光原位杂交（FISH）解释标准中做出了一些重大改变，并增加了FISH模棱两可的病例。建议在最初的HER2FISH结果不明确后重复HER2测试；然而，关于其对最终HER2状态的影响知之甚少.这项研究的目的是调查反射测试是否澄清HER2状态，并描述新定义的HER2模棱两可组的临床病理特征。
方法：回顾了2013年11月至2015年12月期间使用双探针HER2FISH检测进行的886例原发性浸润性乳腺癌连续病例。HER2免疫组织化学（IHC）和FISH测试在初始HER2FISH结果不明确后对不同的组织块或新样本进行。
结果：与2007年指南相比，85例(9.6%)通过使用2013年指南改变了其类别。85例病例的主要变化是HER2FISH阴性类别中57例（6.4％）变为模棱两可，模棱两可的类别病例从36例增加到67例。HER2FISH模棱两可与HER2IHC模棱两可(2+)和17号染色体多体显著相关(P<0.01)。通过IHC和FISH重复测试，在33％和42％的HER2模棱两可的病例中明确了HER2状态，分别。在重复FISH和或IHC测试后，总共32例（48％）初始HER2模棱两可的病例保持HER2模棱两可。这些肿瘤是ER/PR+，KI-67指数高。
结论：新指南对更多HER2FISH模棱两可的病例进行了分类。重复HER2测试澄清了约50％的初始HER2FISH可疑病例中的HER2状态。此外,HER2模棱两可的病例值得进一步研究，因为关于该人群的预后和最佳治疗策略的信息有限。
方法：回顾了2013年11月至2015年12月期间使用双探针HER2FISH检测进行的886例原发性浸润性乳腺癌连续病例。HER2免疫组织化学（IHC）和FISH测试在初始HER2FISH结果不明确后对不同的组织块或新样本进行。
结果：与2007年指南相比，85例(9.6%)通过使用2013年指南改变了其类别。85例病例的主要变化是HER2FISH阴性类别中57例（6.4％）变为模棱两可，模棱两可的类别病例从36例增加到67例。HER2FISH模棱两可与HER2IHC模棱两可(2+)和17号染色体多体显著相关(P<0.01)。通过IHC和FISH重复测试，在33％和42％的HER2模棱两可的病例中明确了HER2状态，分别。在重复FISH和或IHC测试后，总共32例（48％）初始HER2模棱两可的病例保持HER2模棱两可。这些肿瘤是ER/PR+，KI-67指数高。
结论：新指南对更多HER2FISH模棱两可的病例进行了分类。重复HER2测试澄清了约50％的初始HER2FISH可疑病例中的HER2状态。此外,HER2模棱两可的病例值得进一步研究，因为关于该人群的预后和最佳治疗策略的信息有限。
