Dowsett Mitch, Hanna Wedad M, Kockx Mark, Penault-Llorca Frederique, Rüschoff Josef, Gutjahr Thorsten, Habben Kai, van de Vijver Marc J
Academic Depertment of Biochemistry, Royal Marsden Hospital, London, UK.
Mod Pathol. 2007 May;20(5):584-91. doi: 10.1038/modpathol.3800774. Epub 2007 Mar 30.
Human epidermal growth factor receptor 2 (HER2) positivity in breast cancer is a prognostic factor regarding tumor aggressiveness and a predictive factor for response to trastuzumab (Herceptin). Early and accurate HER2 testing of all breast cancer patients at primary diagnosis is essential for optimal disease management. Routine HER2 tests, such as immunohistochemistry and fluorescence in situ hybridization (FISH), are subject to interlaboratory variation, and validation by laboratory proficiency testing is important to improve standardization. This study compared immunohistochemistry and FISH testing between five international pathology reference centers. Each center evaluated 20 immunohistochemistry and 20 FISH breast cancer specimens in five testing rounds. In each round, one center selected two sets of four different invasive tumor specimens (set A for immunohistochemistry and set B for FISH) and sent samples to the other four centers in a blinded manner, while retaining samples for its own evaluation. Results were analyzed by an independent coordinator. With immunohistochemistry, there were no differences between the five centers for any of the specimens at the level of diagnostic decision (positive or negative HER2 status). However, differences between laboratories were observed in immunohistochemistry scoring. Of the 20 specimens, four were scored as negative (0/1+) and five as positive (3+) in all centers; eight were negative or equivocal (2+), and three positive or equivocal. After FISH retesting of nine of the 11 equivocal immunohistochemistry cases, consensus was achieved in 15 of 18 (83%) specimens. FISH analysis of set B specimens resulted in consensus between centers in 16 of 20 (80%) specimens (six negative and 10 positive). All four discordant FISH specimens were scored as having HER2:CEP17 ratios within the range 1.7-2.3 by at least one center. Equivocal immunohistochemistry and borderline FISH cases are difficult to interpret, even for highly experienced and validated laboratories, highlighting the need for quality-control procedures.
人表皮生长因子受体2（HER2）在乳腺癌中的阳性表达是肿瘤侵袭性的一个预后因素，也是对曲妥珠单抗（赫赛汀）反应的一个预测因素。对所有乳腺癌患者在初次诊断时进行早期、准确的HER2检测对于优化疾病管理至关重要。常规的HER2检测，如免疫组织化学和荧光原位杂交（FISH），存在实验室间差异，通过实验室能力验证来提高标准化很重要。本研究比较了五个国际病理参考中心之间的免疫组织化学和FISH检测。每个中心在五个检测轮次中评估20个免疫组织化学和20个FISH乳腺癌标本。在每一轮中，一个中心选择两组四个不同的浸润性肿瘤标本（一组用于免疫组织化学，一组用于FISH），并以盲法将样本发送给其他四个中心，同时保留样本用于自身评估。结果由一名独立协调员进行分析。对于免疫组织化学，在诊断决策水平（HER2状态为阳性或阴性）上，五个中心对任何标本均无差异。然而，在免疫组织化学评分方面观察到了实验室间的差异。在20个标本中，有4个在所有中心均被评为阴性（0/1+），5个被评为阳性（3+）；8个为阴性或可疑（2+），3个为阳性或可疑。在对11例可疑免疫组织化学病例中的9例进行FISH重新检测后，18例标本中有15例（83%）达成了共识。对B组标本的FISH分析在20例标本中有16例（80%）在各中心之间达成了共识（6例阴性和10例阳性）。所有四个不一致的FISH标本在至少一个中心被评为HER2:CEP17比值在1.7 - 2.3范围内。即使对于经验丰富且经过验证的实验室，可疑的免疫组织化学和临界FISH病例也难以解释，这突出了质量控制程序的必要性。
