Somers V A, Pietersen A M, Theunissen P H, Thunnissen F B
Department of Pathology, Maastricht University, The Netherlands.
J Clin Oncol. 1998 Sep;16(9):3061-8. doi: 10.1200/JCO.1998.16.9.3061.
Kirsten ras (K-ras) point mutations are found in 30% to 56% of pulmonary adenocarcinomas by means of highly sensitive techniques. Recently, the Point-EXACCT (point mutation detection using exonuclease amplification coupled capture technique) method was described, which detected one cell with a mutation in 15,000 normal cells. The aim of this study was to examine whether K-ras point mutations could be found with this rapid method in the sputum of patients with adenocarcinoma of the lung.
DNA from paraffin-embedded adenocarcinoma and corresponding sputum samples were analyzed for mutations of the K-ras gene. Twenty-eight biopsy specimens and 54 sputum samples of 22 patients were used for amplification and K-ras codon 12 point mutation detection.
In 11 of 22 patients (50%), a mutation in K-ras codon 12 was shown in the tumor sample. In five of 11 patients (45%) with a K-ras mutation in the tumor, the same type of mutation was identified in at least one sputum sample. A mutation could not be detected in any of the sputum samples from patients with a K-ras-negative tumor. Time between K-ras point mutation detection in sputum and clinical diagnosis of lung cancer varied from 1 month to almost 4 years. In two of the five patients with K-ras-positive sputum specimens, malignant cells were found with cytologic examination.
Point-EXACCT is suitable for the detection of K-ras point mutations in sputum samples of patients with adenocarcinoma of the lung. This approach may be an important adjunct to cytology in the early diagnosis of lung cancer.
通过高灵敏度技术发现，30%至56%的肺腺癌中存在 Kirsten 原癌基因（K-ras）点突变。最近，一种名为Point-EXACCT（利用核酸外切酶扩增耦合捕获技术进行点突变检测）的方法被报道，该方法能在15000个正常细胞中检测到一个携带突变的细胞。本研究的目的是探讨能否用这种快速方法在肺腺癌患者的痰液中检测到K-ras点突变。
对石蜡包埋的腺癌组织及相应痰液样本的DNA进行K-ras基因突变分析。22例患者的28份活检标本和54份痰液样本用于扩增及K-ras密码子12点突变检测。
22例患者中有11例（50%）肿瘤样本显示K-ras密码子12发生突变。11例肿瘤中有K-ras突变的患者中，有5例（45%）在至少一份痰液样本中检测到相同类型的突变。在K-ras基因阴性肿瘤患者的任何痰液样本中均未检测到突变。痰液中检测到K-ras点突变与肺癌临床诊断之间的时间间隔从1个月到近4年不等。在5例K-ras阳性痰液标本患者中的2例，通过细胞学检查发现了恶性细胞。
Point-EXACCT适用于检测肺腺癌患者痰液样本中的K-ras点突变。这种方法可能是肺癌早期诊断中细胞学检查的重要辅助手段。
