直肠系膜脂肪面积与中低位直肠癌异时性肝转移的关系

The relationship between mesorectal fat area and metachronous liver metastasis of mid-to-lower rectal cancer

目的:探讨直肠系膜脂肪面积(mesorectal fat area,MFA)与中低位直肠癌异时性肝转移(metachronous liver metastasis,MLM)的关系。方法:回顾并纳入2016年12月—2019年12月于南通市肿瘤医院行高分辨率磁共振成像(high-resolution magnetic resonance imaging,HR-MRI)的260例中低位直肠癌患者。以入组者行直肠癌根治术为随访起始时间,2022年12月31日为随访截止时间,平均随访(51.5±13.9)个月,随访期间31例发生MLM,229例无MLM。由2名阅片者独立重新判读HR-MRI影像学征象,在肿瘤最大截面的T2加权成像(T2-weighted imaging,T2WI)斜轴位图像上沿直肠系膜筋膜(mesorectal fascia,MRF)进行勾画,获得MFA。采用t检验、秩和检验、χ^(2)检验、Fisher精确概率检验比较两组患者间的临床基线资料、HR-MRI影像学征象和MFA的差异。采用COX回归分析筛选中低位直肠癌患者发生MLM的危险因素。采用Kaplan-Meier生存曲线法分析MLM危险因素的预后作用。结果:MLM组较无MLM组癌胚抗原(carcinoembryonic antigen,CEA)异常率高[17(54.8%)vs 83(36.2%),P=0.046],HR-MRI上的N分期(HR-MRI reported N stage,mrN stage)高[17(54.8%)vs 81(35.4%),P=0.036],HR-MRI上的壁外血管侵犯(HR-MRI reported extramural vascular invasion,mrEMVI)阳性率高[14(45.2%)vs 54(23.6%),P=0.010],MFA值小(9.34±3.77 vs 11.43±5.13,P=0.008)。多因素COX回归分析表明mrN stage阳性、mrEMVI阳性、MFA<14.6 cm2和术前未进行新辅助放化疗(neoadjuvant chemoradiotherapy,nCRT)是直肠癌根治术后发生MLM的危险因素。Kaplan-Meier生存曲线显示mrN stage阳性组、mrEMVI阳性组、MFA<14.6 cm^(2)组的无MLM生存率均显著低于其对应组,而无MLM生存率在是否接受nCRT的两组间差异无统计学意义。结论:MrN stage阳性、mrEMVI阳性、低MFA和术前未进行nCRT是中低位直肠癌患者直肠癌根治术后发生MLM的危险因素。

Objective:To investigate the relationship between mesorectal fat area(MFA)and metachronous liver metastasis(MLM)in mid-to-lower rectal cancer.Methods:A total of 260 patients with mid-to-lower rectal cancer who underwent highresolution magnetic resonance imaging(HR-MRI)in Nantong Tumor Hospital from December 2016 to December 2019 were retrospectively included in the study.The starting time of follow-up was the radical resection of rectal cancer of the enrolled patients,and the follow-up deadline was December 31,2022.The average follow-up period was(51.5±13.9)months.During the followup period,31 patients had MLM and 229 patients had no MLM.HR-MRI findings were reinterpreted independently by two readers,and MFA was obtained by outlined along the mesorectal fascia(MRF)on oblique axial T2-weighted imaging(T2WI)images of the largest cross-section of the rectal tumor.The differences of clinical baseline data,HR-MRI imaging findings and MFA between the two groups were calculated by t test,rank sum test,χ^(2)test and Fisher’s exact test.COX proportional hazards regression models were used to identify risk factors for MLM in patients with mid-to-lower rectal cancer.Kaplan-Meier survival curves were used to analyze the prognostic effects of risk factors for MLM.Result:Compared with non-MLM group,the MLM group patients had higher rate of carcinoembryonic antigen(CEA)abnormality[17(54.8%)vs 83(36.2%),P=0.046],higher rate of HR-MRI reported N stage(mrN stage)[17(54.8%)vs 81(35.4%),P=0.036],higher positive rate of HR-MRI reported extramural vascular invasion(mrEMVI)[14(45.2%)vs 54(23.6%),P=0.010],and lower MFA(9.34±3.77 vs 11.43±5.13,P=0.008).COX regression analysis showed that mrN stage positive,mrEMVI positive,MFA<14.6 cm2 and without preoperative neoadjuvant chemoradiotherapy(nCRT)were independent risk factors for MLM after radical resection of rectal cancer.Kaplan-Meier survival curves showed that the non-MLM free survival rate was significantly lower in mrN stage positive group,mrEMVI positive group and MFA<14.6 cm^(2) group than in their corresponding groups,but there was no statistical difference in non-MLM free survival rate between the two groups receiving nCRT or not.Conclusion:MrN stage positive,mrEMVI positive,low MFA,and without preoperative nCRT were independent risk factors for MLM after radical resection of mid-to-lower rectal cancer.