Challenges Posed to Pathologists in the Detection of KRAS Mutations in Colorectal Cancers
Challenges Posed to Pathologists in the Detection of KRAS Mutations in Colorectal Cancers
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DOI：
10.5858/arpa.2013-0649-oa
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发表时间：
2015-02-01
影响因子：
4.6
通讯作者：
Lin, Ming-Tseh
中科院分区：
文献类型：
--
作者：
Dudley, Jonathan;Tseng, Li-Hui;Lin, Ming-Tseh
背景。- KRAS突变的检测是强制性的，以预测转移性结直肠癌患者对抗表皮生长因子受体单克隆抗体的反应。为了证明在结直肠癌KRAS突变的临床检测病理学家所面临的挑战。在这项焦磷酸测序检测质量评估的回顾性分析中，我们调查了463例福尔马林固定、石蜡包埋的肿瘤组织在26个月内提交用于KRAS突变检测的特征。在39.2%的肿瘤中检测到KRAS突变。这包括2个具有复杂热解谱的肿瘤（密码子12处GGT>GAG和密码子13处GGC>GTT，如通过Pyromaker软件程序解析的）和3个具有不确定百分比的突变等位基因的肿瘤（定义为4%至5%，并通过下一代测序平台确认）。在25例（5.5%）肿瘤细胞低于20%的标本中，22例在化疗/放疗后切除。新辅助治疗后切除的直肠癌（31.0%）与既往未治疗的直肠癌（0%）相比，肿瘤细胞显著减少（P = 0.01）。我们还探索了其他低肿瘤细胞构成的标本以及估计的肿瘤细胞百分比和检测到的突变等位基因频率之间不一致的潜在原因，例如KRAS突变的肿瘤内异质性。新辅助治疗可能耗尽肿瘤细胞，混淆KRAS突变的分子诊断。准确检测肿瘤细胞性差的标本需要适当选择肿瘤组织，评估肿瘤细胞性，使用高灵敏度的检测方法，并进行前瞻性质量评估。
Context.-Detection of KRAS mutation is mandatory to predict response to anti-epidermal growth factor receptor monoclonal antibodies in patients with metastatic colorectal cancers.Objective.-To demonstrate challenges posed to pathologists in the clinical detection of KRAS mutations in colorectal cancers.Design.-In this retrospective analysis for quality assessment of the pyrosequencing assay, we survey the characteristics of 463 formalin-fixed, paraffin-embedded neoplastic tissues submitted for KRAS mutation detection during a 26-month period.Results.-The KRAS mutation was detected in 39.2% of tumors. This included 2 tumors with complex pyrograms (GGT>GAG at codon 12 and GGC>GTT at codon 13, as resolved by a Pyromaker software program) and 3 tumors with an indeterminate percentage of mutant alleles (defined as 4% to 5% and confirmed by a next-generation sequencing platform). Among the 25 specimens (5.5%) with fewer than 20% tumor cells, 22 were resected after chemotherapy/radiation. Significant depletion of tumor cells was observed in rectal cancers resected after neoadjuvant therapy (31.0%) versus those without previous treatment (0%) (P = .01). We also explore other specimens with low tumor cellularity and potential causes of discrepancy between the estimated tumor cell percentage and detected mutant allele frequency, such as intratumor heterogeneity of KRAS mutation.Conclusions.-Neoadjuvant therapy may deplete tumor cells and confound the molecular diagnosis of KRAS mutations. Accurate detection of specimens with poor tumor cellularity requires the appropriate selection of neoplastic tissues, evaluation of tumor cellularity, use of assays with high sensitivity, and prospective quality assessment.