双探针显色和荧光原位杂交法检测乳腺癌HER2基因状态和17号染色体的分析

Comparison between analysis of HER2 gene and chromosome 17 in breast cancer by dual-probe chromogenic in situ hybridization and fluorescence in situ hybridization

目的通过与荧光原位杂交（FISH）比较，评估双探针显色原位杂交（双探针CISH）法在诊断女性乳腺浸润性导管癌HER2基因状态中应用的可靠性，同时探讨17号染色体多倍体对原位杂交诊断HER2基因状态时可能产生的影响。方法收集146例乳腺癌组织的常规石蜡包埋标本，分别用欧盟（CE）认证的FISH（146例）及CISH（73例）HER2／17号染色体着丝粒（CEN17）双探针试剂盒技术，对肿瘤标本的HER2基因状态进行检测，并按照2007年美国临床肿瘤协会及美国病理家协会（ASCO／CAP）标准分别用计算HER2基因拷贝数和（或）计算HER2／CEN17比值的方法对结果进行分析。结果在同时进行FISH和双探针CISH检测的73例标本中发现，两种技术对HER2阴性和阳性的诊断符合率分别为91．7％（33／36）和97．4％（37／38），两者的总体符合率为95．9％（70／73）；在对146例FISH结果的计数分析中，计数HER2基因拷贝数得出不确定诊断的病例量是计数HER2／CEN17得出不确定诊断病例量的1．6倍（13／8）；此外，在FISH和CISH结果中按拷贝数计数为阳性的病例与在按比值计数时却为阴性病例的不吻合率分别为4．8％（3／63）和3．0％（1／33）；同时在FISHHER2阳性病例（HER2／CEN17）中多倍体发生率为63．5％（40／63，P=0．002），高于阴性者中多倍体的发生率（37．3％，28／75）。结论双探针CISH技术检测乳腺癌HER2基因状态的结果和FISH技术检测的结果非常一致，提示两种技术临床诊断价值相近，并且同步检测并计数HER2和17号染色体有助于明确HER2基因状态。

Objective To evaluate the application of dual-probe chromogenic in situ hybridization （dual-probe CISH ） in analysis of HER2 gene status of breast cancer patients by comparison with fluorescence in situ hybridization （FISH）. The potential impact of chromosome 17 polysomy in the determination of HER2 status was also studied. Methods One hundred and forty-six cases of paraffin- embedded breast cancer tissues were retrieved. Analysis of HER2 gene and chromosome 17 copy numbers using CE-approved commercial kits of dual-probe FISH （for 146 cases） and dual-probe CISH （for 73 cases） were carried out. The results were interpreted according to ASCO/CAP,2007 either HER2 gene copy number or the ratio of HER2/centromere 17 （CEN17）. Results Of the 73 cases analyzed by both FISH and dualprobe CISH, the concordance rates for negative and positive results was 91.7% （33/36） and 97.4% （37/38） respectively, while the overall concordance rate between the two methods was 95.9% （70/73）. Of the 146 cases analyzed by FISH, 13 cases were interpreted as equivocal if only HER2 copies were counted, compared with 8 equivocal cases by calculating the ratio of HER2/CEN 17. Moreover, 3 cases （4. 8% ） of the 63 HER2-positive cases determined by HER2 copies turned out to be HER2-negative when determined by the ratio of HER2/CEN 17 ; while using dual-probe CISH, 1 （3.0%） of the 33 positive cases turned out to be negative. In addition, when using FISH, there were more chromosome 17 polysomy cases （63.5%,40/63 ） in the HER2-positive subgroup than HER2-negative subgroup （ 37.3%, 28/75 ） （ P = 0. 002 ）. Conclusions Dual-probe CISH can achieve similar results as compared to FISH, indicating that this technology is a reliable alternative to FISH in HER2 testing. The accuracy can further be improved when HER2 and chromosome 17 are simultaneously tested and counted. words]