Turashvili Gulisa, Lazaro Conxi, Ying Shengjie, Charames George, Wong Andrew, Hamilton Krista, Yee Denise, Agro Evangeline, Chang Martin, Pollett Aaron, Lerner-Ellis Jordan
Department of Pathology and Laboratory Medicine, Mount Sinai Hospital and University of Toronto, Toronto, ON M5G 1X5, Canada.
Hereditary Cancer Program, Catalan Institute of Oncology, ONCOBELL-IDIBELL, 08908 Barcelona, Spain.
Cancers (Basel). 2020 Nov 21;12(11):3468. doi: 10.3390/cancers12113468.
Approximately 25% of women diagnosed with tubo-ovarian high-grade serous carcinoma have germline deleterious mutations in or , characteristic of hereditary breast and ovarian cancer syndrome, while somatic mutations have been detected in 3-7%. We set out to determine the BRCA mutation rates and optimal tissue requirements for tumor BRCA testing in patients diagnosed with tubo-ovarian high-grade serous carcinoma.
Sequencing was performed using a multiplexed polymerase chain reaction-based approach on 291 tissue samples, with a minimum sequencing depth of 500X and an allele frequency of >5%.
There were 253 surgical samples (87%), 35 biopsies (12%) and 3 cytology cell blocks (1%). The initial failure rate was 9% (25/291), including 9 cases (3%) with insufficient tumor, and 16 (6%) with non-amplifiable DNA. Sequencing was successful in 78% (228/291) and deemed indeterminate due to failed exons or variants below the limit of detection in 13% (38/291). Repeat testing was successful in 67% (28/42) of retested samples, with an overall success rate of 86% (251/291). Clinically significant (pathogenic, likely pathogenic) variants were identified in 17% (48/276) of complete and indeterminate cases. Successful sequencing was dependent on sample type, tumor cellularity and size ( ≤ 0.001) but not on neoadjuvant chemotherapy or age of blocks ( > 0.05).
Our study shows a 17% tumor BRCA mutation rate, with an overall success rate of 86%. Biopsy and cytology samples and post-chemotherapy specimens can be used for tumor testing, and optimal tumors measure ≥5 mm in size with at least 20% cellularity.
在被诊断为输卵管卵巢高级别浆液性癌的女性中，约25%在BRCA1或BRCA2基因中存在生殖系有害突变，这是遗传性乳腺癌和卵巢癌综合征的特征，而体细胞突变的检出率为3%-7%。我们旨在确定被诊断为输卵管卵巢高级别浆液性癌的患者中BRCA突变率以及肿瘤BRCA检测的最佳组织要求。
采用基于多重聚合酶链反应的方法对291份组织样本进行测序，最低测序深度为500X，等位基因频率>5%。
有253份手术样本（87%）、35份活检样本（12%）和3份细胞学细胞块样本（1%）。初始失败率为9%（25/291），包括9例（3%）肿瘤量不足和16例（6%）DNA不可扩增。测序成功的占78%（228/291），因外显子失败或变异低于检测限而被判定为不确定的占13%（38/291）。在重新检测的样本中，67%（28/42）重复检测成功，总体成功率为86%（251/291）。在完整和不确定病例中，17%（48/276）鉴定出具有临床意义（致病、可能致病）的变异。成功测序取决于样本类型、肿瘤细胞含量和大小（P≤0.001），但不取决于新辅助化疗或样本块的保存时间（P>0.05）。
我们的研究显示肿瘤BRCA突变率为17%，总体成功率为86%。活检和细胞学样本以及化疗后标本可用于肿瘤BRCA检测，最佳肿瘤大小≥5mm，细胞含量至少20%。
