Preoperative metabolic parameters of 18F-FDG PET/CT are associated with TNM stage and prognosis of colorectal cancer patients.

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Colorectal cancer (CRC) is the third most frequent cause of cancer-related death, while tumor/node/metastasis (TNM) stage of American Joint Committee on Cancer is the guideline of making treatment strategy and predicting survival. The aim of this study is to investigate the association of preoperative 2-deoxy-2[18F]fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT), TNM stage, and prognosis of patients with CRC. From September 2016 to August 2022, a total of 132 patients were retrospectively and consecutively enrolled in this cross-sectional study, who were diagnosed as CRC by histopathology and received preoperative 18F-FDG PET/CT. Firstly, the correlation between the metabolic parameters and clinicopathological features of the primary tumors was investigated. Secondly, univariate and multivariate logistic regression analyses were used to estimate the odds ratio of the association between the clinical and metabolic parameters and the advanced TNM stage (stage III-IV). Thirdly, progression-free survival (PFS) was analyzed using Kaplan-Meier curves and Log-rank test. The results revealed that the metabolic tumor volume (MTV) >6.6 cm3 and serum carcinoembryonic antigen (CEA) >5.84 ng/mL were independently associated with advanced TNM stage (P=0.0009, 0.0011, respectively). Larger tumor size, higher tumor-to-liver standardized uptake value ratio, MTV, and total lesion glycolysis (TLG) were significantly correlated with advanced pT stage (stage 4), and higher TLG and MTV were significantly correlated with advanced pN stage (stage 1-2) (P<0.05), while no metabolic parameters were significantly correlated with metastasis status (P>0.05). Higher serum CEA and carbohydrate antigen 19-9 levels were significantly correlated with advanced pT, pN stage, and metastasis status (P<0.05). Patients were followed up for at least 1 year. The MTV >6.6 cm3 was significantly associated with worse PFS (P=0.032). 18F-FDG PET-CT can serve as a noninvasive tool for preoperatively staging CRC. The MTV >6.6 cm3 might be associated with advanced TNM stage and worse PFS.