The relationship of F-18 FDG PET/CT volumetric parametres with tumor lateralization and TNM stage in patients with colon cancer

Aim: In this study, the relationship between volumetric parameters obtained from F-18 FDG PET/CT images of patients diagnosed with colon cancer and several variables, primarily tumor stage and lateralization, was examined. Materials and Methods: The study included 55 patients who were diagnosed with colon cancer, had not undergone surgery, and underwent F-18 FDG PET/CT for staging purposes in Manisa Celal Bayar University, Faculty of Medicine, Department of Nuclear Medicine. Demographic characteristics (age, gender, weight, height, etc.), clinicopathological characteristics (histological subtype, TNM classification, metastasis site, tumor location) and biochemical parameters such as CEA and CA 19-9 were obtained from the hospital system retrospectively. Metabolic tumor volume (MTV), SUVmax and SUVmean measurements were measured by taking a fixed threshold value of 2.5 and 3.0 SUVmax in the F-18 FDG-PET/CT images taken for staging purposes before the treatment. Total lesion glycolysis (TLG) value was calculated by multiplying the MTV and SUVmean value. The relationship of these recorded data with various parameters such as tumor lateralization, TNM stage, CEA and CA 19-9 were evaluated. Results: Of the 55 patients included in the study, 31 (56.4%) were male and 24 (43.6%) were female, with a mean age of 65.8±13.7 years. The tumor was located in the left colon in 58.2% of the patients. When the clinical stage is evaluated, 50.9% of the patients are Stage 4, 31% are Stage 2, and 16.4% are Stage 3. There was no significant difference between the localization of the primary tumor and the clinical stage of the tumor (p=0.483). There was no significant difference between the localization of the primary tumor and serum CEA and CA 19-9 levels (p=0.577, p=0.912, respectively). No significant correlation was found between T and N stages and serum CEA values (p=0.925, p=0.473, respectively). As T and N stages increased, a significant increase was found in CA 19-9 levels (p=0.042, p=0.014, respectively). Serum CEA and CA 19-9 levels were found to be significantly higher in patients with distant metastases compared to patients without distant metastases (p=0.001, p=0.025, respectively). MTV2.5 and TLG2.5 values were found to be higher in right colon tumors (p=0.008, p=0.023, respectively). MTV3.0 and TLG3.0 values were found to be higher in right colon tumors (p=0.010, p=0.027, respectively). There was no significant difference between T, N and M stages in terms of SUVmax, MTV, TLG parameters (p>0.05). Conclusion: There was no significant relationship between the volumetric parameters obtained from F-18 FDG PET/CT images and the clinical stage of the tumor in patients with a diagnosis of colon. MTV and TLG values were found to be higher in right colon tumors. It was thought that the differences observed in the results of our study and the findings of previous studies conducted for this purpose may be caused by various factors such as the number of patients, patient selection, clinical and tumor-related characteristics of the patients, and observer-related factors. Therefore, prospective studies with a large number of patients will shed more light on this issue in the future.