Value Of Metabolic Parameters Of Preoperative ¹⁸F-FDG PET/CT Imaging In Prognostic Assessment Of Colon Cancer

Objective:To investigate the value of maximum standardized uptake value（SUVmax）,peak standardized uptake normalized to lean body mass（SULpeak）,metabolic Tumor Volume（MTV）and total Lesion Glycolysis（TLG）of ¹⁸F-FDG PET/CT imaging of primary colon cancer in postoperative prognosis assessment of colon cancer.Methods:A retrospective study was conducted,the clinicopathological data of54 patients with colon cancer admitted to the first affiliated hospital of guangxi medical university from May 2014 to August 2018 were collected.All the 54patients underwent preoperative ¹⁸F-FDG PET/CT examination,no preoperative radiotherapy,chemotherapy or other tumor-related treatment was received.After complete examination,the primary and metastatic foci were removed surgically in our hospital,the postoperative pathology of all the 54 patients was colorectal adenocarcinoma,postoperative adjuvant treatment was performed according to the patient’s specific situation and the patient’s intention.Follow-up was conducted by telephone,the follow-up was mainly about the survival of the patients.The total survival time of patients was from the first day after surgery to the end of patient death or follow-up,and the follow-up time was up to June 2019.The measurement data of non-normal distribution are expressed as M(P₂₅,P₇₅).The death of the patient during the follow-up was considered as a positive event.The receiver operating characteristic（ROC）curve was used to calculate the SUVmax,SULpeak,MTV,TLG,maximum tumor diameter,CEA,CA199 and ki-67 curve area（AUC）to obtain the boundary value point.Kaplan-meier method was used for survival analysis.Log-rank test was used for single factor analysis and COX proportional risk model was used for multi-factor analysis.To analyze the relationship between primary lesion SUVmax,SULpeak,MTV and TLG and clinicopathological factors.Mann-whitney U non-parametric test was used for comparison of differences among non-normal distribution data sets,and kruskal-wallis H test was used for comparison of differences among multi-group samples.P<0.05 was considered statistically significant.Results:（1）Analysis of metabolic parameters and clinicopathological factors:SUVmax was related to lesion location and ki-67（U=149、244,P=0.0002,0.037）.SULpeak is related to T stage and clinical stage（H=7.023、9.886,P=0.030,0.020）.MTV was only associated with the maximum tumor diameter（U=135,P=0.00009）.TLG was related to tumor site,tumor maximum diameter and ki-67（U=212、166、247,P=0.009,0.001,0.042）.（2）According to ROC curve analysis:SUVmax AUC=0.564[95%confidence interval（CI）:0.3920.736,P=0.441],SULpeak AUC=0.555[95%CI:0.387-0.723,P=0.509],MTV AUC=0.732[95%CI:0.598-0.866 P=0.005],TLG AUC=0.716[95%CI:0.574-0.857,P=0.009],maximum tumor diameter AUC=0.670[95%CI:0.516-0.824,P=0.041],CEA AUC=0.696[95%CI:0.539-0.853,P=0.018],CA199AUC=0.732[95%CI:0.598-0.866,P=0.005],Ki-67 AUC=0.495[95%CI:0.339-0.650,P=0.949].Since the AUC of SUVmax,SULpeak and ki-67 were small,the median values of SUVmax 9.063,SULpeak 5.318 and ki-67 70 were the grouping boundary points.The best threshold of MTV was 125.873cm3（sensitivity 62.9%,specificity 78.9%）,the best threshold of TLG was 744.258（sensitivity 65.7%,specificity 84.2%）,the optimal threshold of maximum tumor diameter was 5.75cm（sensitivity 54.3%,specificity 73.7%）,the optimal threshold of CEA is 7.025 ng/ml（sensitivity is 80.0%,specificity is 63.1%）,the optimal threshold of CA199 was 14.005 U/ml（sensitivity 88.6%,specificity52.6%）.（3）Single factor analysis shows:Cancer nodules,N stage,M stage,clinical stage,TLG,CEA and CA199 were the influencing factors for the overall postoperative survival rate of colon cancer patients（χ²=5.090、4.370、5.590、7.875、7.837、4.818、4.296,P=0.024,0.037,0.018,0.019,0.005,0.028,0.038）.SUVmax,SULpeak and MTV were not associated with overall survival after colon cancer surgery（P=0.797,0.525,0.185）.Multi-factor analysis shows:TLG was an independent risk factor for overall postoperative survival in colon cancer patients（HR=2.633,95%CI:1.302-5.324,P=0.007）.Conclusion:Among the metabolic parameters of ¹⁸F-FDG PET/CT,TLG is an independent factor affecting the prognosis of patients with colon cancer after surgery.The higher the value of TLG,the worse the prognosis of patients with colon cancer after surgery.SUVmax,SULpeak and MTV were not associated with postoperative outcomes of patients with colon cancer.