18F-FDG PET/CT related parameters can predict postoperative prognosis of colorectal cancer

Objective To explore the clinical value of 18F-FDG PET/CT-related parameters for the prediction of tumor disease-free survival time (DFS) and overall survival time (OS) after the radical resection of colorectal cancer (CRC). Methods Retrospective analysis was conducted on 132 patients (93 males and 39 females; median age, 63 years) with CRC who underwent 18F-FDG PET/CT examination between November 2011 and October 2016. The 18F-FDG PET/CT-related parameters were as follows: SUVmax=2.5 (20%, 30%, 40%, and 50% of SUVmax were used as different thresholds); SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of different thresholds; and DFS and OS of CRC patients after radical resection. The receiver-operating characteristic (ROC) curve was used in the measurement of the area under curve of 18F-FDG PET/CT-related parameters and the optimal DFS cutoff value. Survival analysis was performed with the Kaplan-Meier method. Univariate and multivariate analyses were performed with Log-rank test and the COX proportional hazards model, respectively. Results The ROC curve predicted the DFS cut off value, and SUVmax=19.36, MTV= 22.64 cm3, TLG= 117.78 g, TLG20% = 129.74 g, TLG30% = 107.05 g, TLG40% = 73.22 g, and TLG50% = 56.13 g. DFS univariate analysis showed that CEA, CA19-9, lymph node metastasis, clinical stage, chemotherapy, SUVmax, MTV, TLG, TLG20%, TLG30%, TLG40%, and TLG50% were the factors influencing postoperative DFS. Multivariate analysis showed that SUVmax (95%CI: 1.882–5.815, OR= 3.308, P<0.000), clinical stage (95%CI: 1.226–3.819, OR = 2.164, P=0.008), and CA19-9 (95%CI: 1.182–3.724, OR=2.098, P= 0.011) were independent risk factors for postoperative DFS. The survival analysis of OS univariate analysis showed that CEA, CA19-9, histological type, SUVmax, MTV, TLG, TLG20%, TLG30%, TLG40%, and TLG50% were the factors influencing postoperative OS. Furthermore, SUVmax (95%CI: 1.129–6.624, OR=2.735, P=0.026), TLG50% (95%CI: 1.640–19.801, OR=5.699, P=0.006), and CA19-9 ( 95%CI: 1.868–11.084, OR=4.550, P=0.001) were the independent risk factors for postoperative OS. Conclusion 18F-FDG PET/CT-related parameters SUVmax and TLG50% can predict the prognosis of patients with CRC; the higher the parameter values are, the worse the prognoses are. Key words: Colorectal neoplasms; Positron emission tomography computed tomography; Fluorodeoxyglucose F18; Prognosis