Department of Hepato-Gastroenterology, Digestive Oncology Unit, Ghent University Hospital, De Pintelaan 185 1K12IE, 9000 Ghent, Belgium.
BMC Cancer. 2010 May 11;10:189. doi: 10.1186/1471-2407-10-189.
With the availability of effective anti-EGFR therapies for various solid malignancies, such as non-cell small lung cancer, colorectal cancer and squamous cell carcinoma of the head and neck, the knowledge of EGFR and K-RAS status becomes clinically important. The aim of this study was to analyse EGFR expression, EGFR gene copy number and EGFR and K-RAS mutations in two cohorts of squamous cell carcinomas, specifically anal canal and tonsil carcinomas.
Formalin fixed, paraffin-embedded tissues from anal and tonsil carcinoma were used. EGFR protein expression and EGFR gene copy number were analysed by means of immunohistochemistry and fluorescence in situ hybridisation. The somatic status of the EGFR gene was investigated by PCR using primers specific for exons 18 through 21. For the K-RAS gene, PCR was performed using exon 2 specific primers.
EGFR immunoreactivity was present in 36/43 (83.7%) of anal canal and in 20/24 (83.3%) of tonsil squamous cell carcinomas. EGFR amplification was absent in anal canal tumours (0/23), but could be identified in 4 of 24 tonsil tumours.From 38 anal canal specimens, 26 specimens were successfully analysed for exon 18, 30 for exon 19, 34 for exon 20 and 30 for exon 21. No EGFR mutations were found in the investigated samples. Thirty samples were sequenced for K-RAS exon 2 and no mutation was identified. From 24 tonsil specimens, 22 were successfully analysed for exon 18 and all 24 specimens for exon 19, 20 and 21. No EGFR mutations were found. Twenty-two samples were sequenced for K-RAS exon 2 and one mutation c.53C > A was identified.
EGFR mutations were absent from squamous cell carcinoma of the anus and tonsils, but EGFR protein expression was detected in the majority of the cases. EGFR amplification was seen in tonsil but not in anal canal carcinomas. In our investigated panel, only one mutation in the K-RAS gene of a tonsil squamous cell carcinoma was identified. This indicates that EGFR and K-RAS mutation analysis is not useful as a screening test for sensitivity to anti-EGFR therapy in anal canal and tonsil squamous cell carcinoma.
随着针对各种实体恶性肿瘤（如非小细胞肺癌、结直肠癌和头颈部鳞状细胞癌）的有效抗 EGFR 治疗方法的出现，EGFR 和 K-RAS 状态的知识在临床上变得非常重要。本研究的目的是分析两个队列的鳞状细胞癌（特别是肛门和扁桃体癌）中的 EGFR 表达、EGFR 基因拷贝数以及 EGFR 和 K-RAS 突变。
使用来自肛门和扁桃体癌的福尔马林固定、石蜡包埋组织。通过免疫组织化学和荧光原位杂交分析 EGFR 蛋白表达和 EGFR 基因拷贝数。使用针对外显子 18 到 21 的特异性引物通过 PCR 研究 EGFR 基因的体细胞状态。对于 K-RAS 基因，使用外显子 2 特异性引物进行 PCR。
36/43（83.7%）例肛门管和 20/24（83.3%）例扁桃体鳞状细胞癌存在 EGFR 免疫反应性。肛门管肿瘤中不存在 EGFR 扩增（0/23），但在 4 例扁桃体肿瘤中可以识别。在 38 例肛门管标本中，26 例成功分析了外显子 18，30 例分析了外显子 19，34 例分析了外显子 20，30 例分析了外显子 21。在所研究的样本中未发现 EGFR 突变。对 30 个样本进行了 K-RAS 外显子 2 的测序，未发现突变。在 24 个扁桃体标本中，22 个成功分析了外显子 18，所有 24 个标本都分析了外显子 19、20 和 21。未发现 EGFR 突变。对 22 个样本进行了 K-RAS 外显子 2 的测序，发现一个突变 c.53C > A。
肛门和扁桃体鳞状细胞癌中不存在 EGFR 突变，但大多数病例存在 EGFR 蛋白表达。在扁桃体癌中观察到 EGFR 扩增，但在肛门管癌中未观察到。在所研究的面板中，仅在一个扁桃体鳞状细胞癌的 K-RAS 基因中发现一个突变。这表明在肛门管和扁桃体鳞状细胞癌中，EGFR 和 K-RAS 突变分析作为抗 EGFR 治疗敏感性的筛选试验并不有用。
