Comparison of semiquantitative metabolic parameters of the primary tumor obtained in PET/CT with 18F-FDG and 18F-FLT in patients with cervical cancer.

AIM: The aim of the study was to compare semiquantitative metabolic parameters of primary tumor assessed in vivo in 18F-FDG- and 18F-FLT in cervical cancer patients. MATERIAL & METHODS: 39 patients with histologically confirmed cervical cancer underwent PET/CT scans acquired on separate days 60 min after i. v. injection of 364 ±â€Š75 MBq of 18F-FDG and 259 ±â€Š40 MBq of 18F-FLT. The reconstructed PET images were evaluated using a dedicated workstation for primary tumor semiquantitative parameters: SUVmax, MTV, TLG (for 18F-FLT-TLP) and heterogeneity (AUC-CSH). Wilcoxon-Mann-Whitney test and ROC curves were used for statistical analysis. Based on data from the local cancer registry and 3y- to -5y follow up patients were divided into 2 groups with regard to prognosis. Also differences between histopathological type and FIGO classification in two tracers were assessed. RESULTS: Depending on PET/CT results, patients were divided into 3 groups: group 1 with disease limited only to the cervix, group 2 with disease limited to the cervix and iliac lymph nodes, and group 3 with disseminated disease. Statistically significant differences were found between keratinizing and non-keratinizing SCC in SUVmax (p = 0.03) and AUC-CSH (p = 0.04) only in 18F-FLT-PET/CT. Following cut-off values for nodal involvement in SUVmax, MTV, TLG/TLP and AUC-CSH were calculated using ROC curves: 13.5, 39.22, 255.94, 0.59 respectively for 18F-FDG and 12.1, 37.59, 140.01, 0.46 respectively for 18F-FLT. Higher values in both tracers in MTV and TLG/TLP were found in a group with worse prognosis. CONCLUSION: This preliminary study suggests that higher values in MTV and TLG/TLP in both tracers might be associated with worse outcome in cervical cancer patients.

Assessment of biological parameters in head and neck cancer based on in vivo distribution of 18F-FDG-FLT-FMISO-PET/CT images.

OBJECTIVE: Several genetic analyses have identified tumor diversity not only among tumors from different patients (intertumor heterogeneity) but also within individual tumors (intratumor heterogeneity). The aim of this study was to analyze the intratumor heterogeneity and other biological parameters based on in vivo distribution in triple-tracer positron emission tomography with computed tomography (PET/CT) study in patients with newly diagnosed head and neck (H&N) cancer. METHODS: Thirty-six patients with newly diagnosed H&N cancer were included in the study. Institutional Bioethical Committee approved the study protocol and informed consent was received from every participant. All patients underwent series of 3 PET/CT scans with [18F]Fluorodeoxyglucose (18F-FDG-PET), [18F]Fluorothymidine (18F-FLT-PET), and [18F]Fluoromisonidazole (18F-FMISO-PET) before treatment. Scans were performed on separate days, within a timeframe of 2 weeks. Several PET/CT parameters grading tumor biology including maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG), its equivalent (total hypoxic lesion [TLH] and total proliferative lesion [TLP]), and heterogeneity (area under the curve-cumulative SUV histogram) for the primary tumor were compared. RESULTS: All patients showed increased uptake of 18F-FDG in primary tumor, ranging from 2.29 to 14.89 SUVmax. Respectively, SUVmax values for 18F-FLT ranged from 0.93 to 16.11 and for 18F-FMISO 0.36-4.07. Based on 3-year follow-up, we divided patients in terms of survival forecasts (first with good prognosis and second with worse). Higher values of TLG/TLP/TLH and SUVmax were observed in the second group in all 3 tracers (for 18F-FDG: 167.40 vs 100.32, 11.15 vs 8.95; for 18F-FLT: 116.61 vs 60.67, 7.09 vs 5.47; for 18F-FMISO: 37.34 vs 22.30, 1.70 vs 1.61 respectively). Statistically significant differences were shown in SUVmax in 18F-FDG and 18F-FLT (P<0.034, P<0.034, respectively; in TLG, P=0.05; TLP, P=0.04; and TLH, P=0.05). CONCLUSION: Our preliminary results suggest worse prognosis in patients with higher heterogeneity values of primary tumor in proliferation and hypoxia images and combination of metabolic and volumetric parameters in TLG and its equivalent and heterogeneity of primary tumor seems to be a prognostic factor.