He effect of volumetric parameters in baseline 18F-FDG PET/CT and the change of these parameters in 18F-FDG PET/CT after treatment on general survival in malign plevral mesothelioma patients receiving chemotherapy

THE EFFECT OF VOLUMETRIC PARAMETERS IN BASELINE 18F FDG PET/CT AND THE CHANGE OF THESE PARAMETERS IN 18F-FDG PET/CT AFTER TREATMENT ON GENERAL SURVIVAL IN MALIGN PLEVRAL MESOTHELIOMA PATIENTS RECEIVING CHEMOTHERAPY Purpose: Malignant mesothelioma; It is a rare malignancy with a poor prognosis originating from the mesothelial surface of structures such as the pleura, peritoneum, pericardium, and tunica vaginal. Imaging methods are used to evaluate the diagnosis, prognosis, and treatment response of malignant mesothelioma. In our study, we aimed to examine the effects of PET-CT parameters on predicting survival in patients with malignant pleural mesothelioma. Methods: The data of 36 patients with malignant mesothelioma, whose data were available, were reviewed retrospectively. Patients who had PET-CT scans before treatment and second PET-CT scans for treatment response evaluation were included in the study. Demographic characteristics of the patients, laboratory, pre- and post treatment PET-CT images were analyzed from the hospital registry system. The parameters obtained in PET-CT before the treatment were expressed as SUVmax1, MTV1, TLG1, Pleural thickness1 and the parameters obtained in PET-CT after the treatment were expressed as SUVmax2, MTV2, TLG2, Pleural thickness2. The results of the post-treatment PET-CT images of the patients and the changes in the parameters compared to the pre-treatment PET-CT were expressed as ΔMTV, ΔTLG, ΔSUVmax, and ΔPleura thickness as percentage changes. Results: Of the 36 patients included in the study, 19 (52.8%) were male and 17 (47.2%) were female. The median age of the patients was 57.5 years (35-76). The median follow-up period of the patients was 15.9 months (3-43). The median ΔMTV of the surviving patients was -61.80 ([-100]-165) cm3, and the median of the deceased patients was -9.22 ([-100]-582) cm3 (p=0.65). The median ΔTLG of the surviving patients was -77 ([-100]-326) ml*cm3, and 6.45 ([-100]-1132) ml*cm3 for the deceased patients (p=0.002). When the patients were examined in terms of ΔSUVmax, v the median of the patients who survived was -24.39 ([-100]-45), and the median of the patients who died was 0.57 ([-61]-100) (p=0.381). The median ΔPleural Thickness of surviving patients was -17.36 ([-61]-180), and the median of those who died was 0.69 ([-78]-260) (p=0.373). By performing ROC analysis, patients were divided into two groups according to the cut-off values determined for the parameters and their survival status was examined. Median survival for all patients was 18.8 months (95%CI=13.9-23.6). Median survival was 29.9 (95% CI=15.3-44.4) months for patients with a TLG2 value <158, and 16 (95% CI=9-23) for patients with a TLG2 value >158 (P=0.009). Survival was 29.9 (95% CI=15.3-44.4) months for patients with MTV2 <63.9, and median survival was 16 (95% CI=8.9-23) for patients with >63.9 (p=0.007). Median survival for patients with ΔMTV <-54.03 29.9 (95% CI=27.5-32.2) months, median survival for patients >-54.03 16 (95% CI=12.4- 19.5) months (p=0.002). The median survival of the group with ΔTLG <-62.58 was 30.9 (95% CI=28-33.7) months, the median survival for patients with >-62.58 was 16 (95% CI=12.1-19.8) was detected (p=0.001). Median survival for patients with TBR2 <1.84 was 29.9 (95% CI=14-45.7) months, and median survival for patients with >1.84 was 16 (95% CI=11.2-20.7) detected (p=0.039). For patients with SUVmax1 value <7.95, the median survival was 29.3 months (95% CI=14-44.6), and for patients with >7.95, the median survival was 17.1 months (95% CI=15.2-19)(p=0.312). According to ΔPleural thickness, the median survival for responding patients was 29.3 months (95% CI=15.6-43), and the median survival for nonresponders was 17.1 months (95% CI=14.8-19.3)(p=0.182). Conclusion: Although there are studies in which ∆SUVmax metabolic parameters are associated with survival, there is no clear consensus on this issue. Pleural thickness and ∆pleural thickness was not found to be significant in predicting survival. Volumetric parameters such as ∆MTV and ∆TLG were found to be statistically significant in predicting overall survival both in our study and in studies in the literature. Based on this, it can be said that the volumetric parameters obtained in PET CT are more valuable than metabolic parameters and pleural thickness in demonstrating survival. More studies are needed for this result to be generally accepted and used clinically.