术前CT特征无创预测直肠癌KRAS基因突变的研究

Preoperative CT features for noninvasive prediction of KRAS gene mutations in rectal cancer

目的探讨利用术前多层螺旋CT(MSCT)征象预测直肠癌KRAS基因突变的可能性。方法回顾性分析2016年10月至2017年12月中山大学附属第一医院52例直肠癌患者的临床病理特征、影像学特征及KRAS基因检测结果。建立二分类Logistics回归模型,推测CT参数预测KRAS基因突变的可能性,受试者工作特征曲线(ROC)分析诊断效果及临界点。结果KRAS基因突变者18例(34.6%),患者更易发生淋巴结转移(67.6%vs 32.4%,χ^2=7.53,P=0.010),直肠上静脉(SRV)直径为(5.07±1.00)mm,显著大于非突变患者的(4.23±1.02)mm,差异有统计学意义(t=2.84,P=0.010)。Logistics回归模型显示,淋巴结转移患者发生基因突变的可能性是无淋巴结转移患者的5.69倍(95%CI:1.34~24.14),SRV每增加1 mm,基因突变的可能性增加2.56倍(95%CI:1.14~5.73)。SRV的最佳临界点是4.5 mm,结合影像学淋巴结转移,MSCT预测KRAS突变的敏感度为72.22%(13/18),特异度为85.29%(29/34),总体准确性为80.77%(42/52)。结论利用MSCT静脉期轴位测量SRV直径,可无创预测直肠癌KRAS基因突变可能性,结合淋巴结转移情况,能进一步提高诊断效能。

Objective To explore the feasibility of predicting KRAS gene mutation in rectal cancer by preoperative multi-slice spiral CT(MSCT).Methods From October 2016 to December 2017,clinical data of fifty-two patients with rectal cancer in the First Affiliated Hospital of Sun Yat-sen University were analyzed,including the preoperative imaging parameters,pathological data and KRAS gene detection results.Binary Logistic regression models were established to speculate the possibility of predicting KRAS gene mutation by CT parameters,and the diagnostic effect and critical point were analyzed by receiver operating characteristic curve(ROC).Results Among the 52 cases,18 cases(34.6%)had KRAS gene mutation and were prone to lymph node metastasis(67.6%vs 32.4%,χ^2=7.53,P=0.010).The diameter of superior rectal vein(SRV)was(5.07±1.00)mm in mutation patients,which was significantly larger than that in nonmutation patients(4.23±1.02)mm,the difference was statistically significant(t=2.84,P=0.010).Logistic regression model showed that the probability of gene mutation in patients with lymph node metastasis was 5.69 times higher than that in patients without lymph node metastasis(95%CI:1.34-24.14).For every 1 mm increase in SRV,the probability of gene mutation increased by 2.56 times(95%CI:1.14-5.73).The best threshold of SRV was 4.5 mm.Combined with imaging lymph node metastasis,the sensitivity,specificity and accuracy of MSCT in predicting KRAS mutation were 72.22%(13/18),85.29%(29/34)and 80.77%(42/52),respectively.Conclusions KRAS mutations in rectal cancer can be predicted noninvasively using MSCT to measure SRV diameter in the axial venous phase.Combined with the presence or absence of lymph node metastasis,the diagnostic efficacy can be improved.