蜡块保存年限对乳腺癌HER2基因荧光原位杂交结果的影响

Influence of paraffin block age on the results of fluorescence in situ hybridization of HER2 gene in archival breast cancer samples

目的以浸润性乳腺癌HER2基因表达为研究对象,探讨蜡块保存年限对HER2基因荧光原位杂交(FISH)检测结果的影响。方法回顾性收集2012年1月至2017年12月在首都医科大学附属北京友谊医院病理科初诊为原发浸润性乳腺癌的石蜡样本70例,其中免疫组织化学检测HER2蛋白2+且FISH检测HER2基因扩增的病例每年度10例,共60例,归为Fp组,包括手术切除标本32例,穿刺标本28例;另外选取2012年1月至2012年12月HER2蛋白2+且FISH检测HER2基因未扩增的病例10例,作为阴性对照,归为Fn组,包括手术切除标本5例,穿刺标本5例。将所有病例的归档蜡块以4μm厚度连续切片2张,一张用于苏木精和伊红染色以确定肿瘤位置,另一张重新进行FISH检测,切片预处理采用高温高压热修复方法,胃酶消化使用光学显微镜观察控制。最后按照乳腺癌HER2检测指南(2019版)进行判读并将计数的平均HER2拷贝数/细胞、平均CEP17拷贝数/细胞以及HER2/CEP17比值与初诊结果进行对比。结果Fp组60张切片中,除1张2016年的穿刺组织杂交失败外,其余组织均杂交成功,成功率为98.33%(59/60),成功的切片均判读为阳性,与初诊结果符合率为100%;Fn组10张切片全部杂交成功且均判读为阴性,与初诊结果符合率为100%。Fp组、Fn组中平均HER2拷贝数/细胞、平均CEP17拷贝数/细胞以及HER2/CEP17比值与初诊结果相比,差异均无统计学意义(P>0.05)。结论保存5~10年的乳腺癌归档蜡块,采用高温高压热修复后行HER2基因FISH检测,成功率高、结果准确,可为初诊HER2 IHC 2+但未行FISH检测的癌转移患者在抗HER2靶向用药的筛选中提供一定的依据。

Objective To investigate the influence of paraffin block age on the results of fluorescence in situ hybridization(FISH)of HER2 gene amplification in archival breast cancer samples.Methods Paraffin samples of 70 patients with invasive primary breast cancer initially diagnosed in the Department of Pathology,Beijing Friendship Hospital,Capital Medical University from January 2012 to December 2017 were retrospectively collected.Among them,60 cases(10 cases per year)of HER2 protein 2+by immunohistochemistry and HER2 gene amplification by FISH were classified as Fp group,including 32 excisional biopsy cases and 28 core needle biopsy cases.In addition,10 cases with HER2 protein 2+and HER2 gene non-amplification by FISH from January 2012 to December 2012 were selected as negative control and classified into Fn group,including 5 excisional biopsy cases and 5 core needle biopsy cases.Two consecutive sections of each archived paraffin block were made with the thickness of 4μm.One was used for HE staining to determine the tumor location,and the other was used for repeated FISH detection.The pretreatment of FISH sections was performed by high-temperature and high-pressure thermorepair method,and the gastric enzyme digestion was observed and controlled by optical microscope.Finally,interpretation was performed according to breast cancer HER2 Detection Guidelines(2019 edition)and the counted mean copy number of HER2/cell,mean copy number of CEP17/cell,and HER2/CEP17 ratio were compared with the results of primary results.Results In the 60 sections of Fp group,except for one core needle biopsy tissue in 2016 failed to hybridization,the rest tissues were successfully hybridized,with a success rate of 98.33%(59/60).All successful sections were interpreted as positive,and the coincidence rate with the initial diagnosis results was 100%.All the 10 slices of Fn group were successfully hybridized.All the successful slices were interpreted as negative,and the coincidence rate with the initial diagnosis results was 100%.There were no significant differences in the mean copy number of HER2/cell,mean copy number of CEP17/cell and HER2/CEP17 ratio in Fp group and Fn group compared with the results of initial diagnosis(P>0.05).Conclusion Breast cancer archival paraffin blocks stored for 5-10 years were tested for HER2 gene FISH after high-temperature and high-pressure thermorepair,with a high success rate and accurate results.It can provide a certain basis for screening anti-HER2-targeting drugs for cancer metastatic patients who have not received FISH detection in initial diagnosis.