结直肠癌患者KRAS、NRAS、BRAF及PIK3CA基因突变与其临床病理特征关系的研究

Relationship between KRAS, NRAS, BRAF and PIK3CA gene mutations and clinicopathological features in patients with colorectal cancer

目的 探讨结直肠癌(colorectal cancer, CRC)患者KRAS、NRAS、BRAF、PIK3CA基因突变情况及其与临床病理特征的关系。方法 收集2012—2016年复旦大学附属上海市第五人民医院手术切除的91例原发性CRC患者肿瘤手术切除标本进行回顾性分析,采用扩增阻碍突变系统(ARMS)进行实时荧光定量PCR检测KRAS、NRAS、BRAF、PIK3CA基因突变情况,应用统计学分析其与临床病理学特征的关系。结果 91例CRC患者中,KRAS/NRAS/BRAF/PIK3CA总突变率为53.8%(49/91),其中KRAS突变率为40.7%(37/91),NRAS突变率为4.4%(4/91),BRAF突变率为3.3%(3/91),PIK3CA突变率为2.2%(2/91),KRAS/PIK3CA双突变率为2.2%(2/91),KRAS/NRAS双突变率为1.1%(1/91)。BRAF基因在低分化癌患者中突变率显著高于中-高分化癌患者(P<0.05)。PIK3CA基因突变与肿瘤原发部位有关(P<0.05)。有淋巴结转移患者的KRNS/NRAS/BRAF/PIK3CA基因突变率(78.3%,18/23)显著高于无淋巴结转移患者的基因突变率(45.6%,31/68)(P<0.05)。结论 结直肠癌患者中,KRAS突变最常见,部分患者抗EGFR治疗耐药可能是由于PIK3CA基因突变导致,KRAS/NRAS/BRAF/PIK3CA基因突变与部分临床病理特征存在相关性,但需要更多病例进一步研究证实。

Objective To investigate the mutations status of KRAS, NRAS, BRAF, PIK3CA and its associations with clinicopathological characteristics in colorectal cancer(CRC). Methods Surgical resection specimens of 91 patients with primary CRC from 2012 to 2016 in Shanghai Fifth People’s Hospital affiliated to Fudan University were collected for a retrospective analysis. Real-time fluorescence quantitative PCR was used to detect mutations in KRAS, NRAS, BRAF and PIK3CA genes using amplification-refractory mutation system(ARMS). The relationship between each gene mutation and clinicopathological features was analyzed by statistical analysis. Results Among 91 CRC patients, the total mutation rate of KRAS/NRAS/BRAF/PIK3CA was 53.8%(49/91), with KRAS, NRAS, BRAF, PIK3CA mutation rate was 40.7%(37/91), 4.4%(4/91), 3.3%(3/91) and 2.2%(2/91), respectively. KRAS/PIK3CA double mutation rate was 2.2%(2/91), and KRAS/NRAS double mutation rate was 1.1%(1/91). The mutation rate of BRAF gene in patients with poorly differentiated cancer was significantly higher than that in patients with moderate to well differentiated cancer(P<0.05). PIK3CA gene mutation was significantly different among primary tumor sites(P<0.05).The mutation rate of KRAS/NRAS/BRAF/PIK3CA gene in patients with lymph node metastasis(78.3%, 18/23) was significantly higher than that in patients without lymph node metastasis(45.6%, 31/68)(P<0.05). Conclusion KRAS mutations are most commonly identified in patients with colorectal cancer. PIK3CA mutation is often accompanied by KRAS gene mutation, and EGFR treatment resistance in KRAS wild-type patients may be caused by PIK3CA gene mutation. Simultaneous detection of KRAS/NRAS/BRAF/PIK3CA gene mutations prior to treatment helps to develop the most accurate treatment for colorectal patients. KRAS/NRAS/BRAF/PIK3CA gene mutations are correlated with some clinicopathological features in this group of colorectal cancer patients, but more cases need to be confirmed by further studies.