Value of 18F-FDG PET/CT metabolic parameters in predicting the prognosis of patients with oligometastatic colorectal cancer after radical treatment

Objective To investigate the value of 18F-FDG PET/CT metabolic parameters in predicting the prognosis of patients with oligometastatic colorectal cancer (CRC) after radical treatment. Methods A retrospective analysis was performed for the clinical data of 82 patients who had pathologically confirmed oligometastatic CRC and underwent radical treatment, and according to the presence or absence or progression during follow-up, they were divided into progression group with 49 patients and non-progression group with 33 patients. Preoperative 18F-FDG PET/CT metabolic parameters were collected from all patients, as well as clinical features including clinical stage, primary tumor location, degree of tumor differentiation, neurovascular invasion, vascular tumor thrombus, and preoperative carcinoembryonic antigen. Kaplan-Meier survival analysis and Schoenfeld residual ana-lysis were used to assess the proportional hazards assumptions of categorical variables and continuous variables. According to the type of variables and the results of proportional hazards assumptions, the log-rank test, univariate Cox regression analysis, and Cox regression model with time-dependent covariates were used to perform the univariate analysis. The factors with a significant impact on prognosis were included in the Cox regression model with time-dependent covariates for multivariate analysis, and a binary logistic regression analysis was performed for independent influencing factors. The receiver operating characteristic (ROC) curve was plotted to analyze the predictive performance of independent influencing factors. Results The univariate Cox regression analysis showed that there were significant differences between the two groups in clinical stage (χ2=11.538,P<0.05), preoperative MTV (HR=1.023,95%CI=1.012-1.034,P<0.05), and TLG (HR=1.002,95%CI=1.001-1.003,P<0.05). The multivariate Cox regression analysis with time-dependent covariates showed that clinical stage (HR=2.636,95%CI=1.476-4.780,P<0.05) and preoperative MTV (HR=1.024,95%CI=1.013-1.035,P<0.05) were independent influencing factors for the prognosis of patients with oligometastatic CRC after radical treatment. The ROC curve analysis showed that preoperative MTV had an optimal cut-off value of 13.94 cm3 in predicting the prognosis of patients with oligometastatic CRC after radical treatment, with an area under the ROC curve (AUC) of 0.738 (95%CI=0.627-0.848,P<0.05), a sensitivity of 75.8%, and a specificity of 63.3%. The combination of clinical stage and preoperative MTV had an AUC of 0.801 and a sensitivity of 81.6%. Conclusion An advanced clinical stage and a high preoperative MTV value are associated with a poorer prognosis in patients with oligometasta-tic CRC after radical treatment.