Prognostic value of volumetric F-18 FDG PET/BT parameters in rectum cancer

In this thesis study, it was aimed to determine the relationship between the survival and the volumetric pretreatment F-18 FDG PET / CT parameters in rectal cancer patients. F-18 FDG PET / CT scans of the rectal cancer patients, which performed in the Bursa Uludag University Nuclear Medicine department, retrospectively screened. Between November 2011 and May 2018, there were 112 rectal cancer patients with pretreatment F-18 FDG PET / CT. Metabolic tumor volume (MTV), total lesion glycolysis (TLG), SUVmax, and SUVmean were calculated at the workstation. The relationship between overall survival, local recurrence, and progression-free survival with individual clinical (age, pT, pN) and PET parameters (SUVmax, SUVmean, MTV, TLG) were examined in univariate and multivariate Cox regression analysis. Survival curves were determined using the Kaplan-Meier method. During follow-up (27.1 ± 17.9 months) period, 13 (11.6%) patients died. Metastasis occurred in 27 (24.1%) cases and 8 (7.1%) patients diagnosed with local recurrence. TLG (HR 0.955 95% CI 0.920-0.993, p=0.001) and age (HR 0.955 95% CI 0.920-0.993, p=0.020) were determined to have predictive value for distant metastasis in both univariate and multivariate analyzes. In Kaplan-Meier analysis, TLG (log rank p=0.019), MTV (log rank p=0.035) and SUVmax (log rank p=0.007) were significant for progression-free survival. MTV (HR 1.011 95% CI 1.005-1.017, p<0.001) and age (HR 0.904% 95 CI 0.849-0.963, p= 0.002) were found to be independent risk factors for overall survival in both univariate and multivariate analysis. In the Kaplan-Meier analysis, SUVmax (log rank p=0.018) and MTV (log rank p=0.046) were found significant for overall survival. Our thesis study suggests that pretreatment TLG and MTV, which are volumetric parameters, can be used as prognostic markers for survival in non-metastatic rectal cancer. Further studies and randomized clinical trials are still needed to reach a definitive conclusion in this regard.