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.
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。