The effectiveness of F-18 FDG PET/BT in evaluating response to treatment in cancer patients receiving nivolumab treatment

The Effectiveness of F-18 FDG PET/CT in Evaluating Response to Treatment in Cancer Patients Receiving Nivolumab Treatment The aim of the study is to examine the effectiveness of metabolic and volumetric parameters related to the tumor, the activity of non-tumor hematopoietic tissue and immunity-related side effects obtained from pre- and post-treatment F-18 FDG PET/CT images in evaluating treatment response and their relationship with survival in patients receiving nivolumab therapy. A total of 90 patients who underwent F-18 FDG PET/CT imaging pre and post nivolumab treatment were included in the study. The response to nivolumab treatment was assessed by examining PET/CT images according to PERCIST criteria and patients were divided in to groups as complete metabolic response, partial metabolic response, stable metabolic disease and progressive metabolic disease. Patients then were divided into groups as responders and non-responders to treatment, those with controlled disease and those without. The SUVmax, SUVmean, SUVmin, total MTV, total TLG values, as well as the spleen/liver SUV values and bone marrow/liver SUV values for all tumoral lesions were extracted from PET/CT images taken prior to and following treatment. Additionally, the immunotherapy-related side effects were evaluated visually. An analysis was conducted to explore the correlation between the identified PET/CT parameters, immune-related side effects, treatment response and survival outcomes. In our investigation, we observed that metabolic and volumetric parameters exhibited a significant reduction post-treatment in patients who demonstrated a positive response to therapy and maintained disease control. In patients who did not respond to treatment and whose disease remained uncontrolled, the values of spleen/liver SUVmax, spleen/liver SUVmean, spleen/liver SUVmin, bone marrow/liver SUVmax, bone marrow/liver SUVmean, and bone marrow/liver SUVmin were markedly elevated following treatment compared to their pre-treatment levels. Furthermore, the mean survival duration for patients who responded favorably to treatment was considerably greater than that of those who did not. Additionally, no statistically significant differences were identified between patients who experienced immune-related adverse effects and their treatment response or disease control status. In this research, we demonstrated that the evaluation of F-18 FDG PET/CT in cancer patients undergoing nivolumab therapy revealed that alterations in tumor metabolic and volumetric parameters, as well as the activity of non-tumor hematopoietic tissue derived from PET/CT imaging, could be significant indicators of treatment response. Keywords: Nivolumab, İmmunotherapy, F-18 FDG, PET/CT, SUVmax, Spleen, Bone Marrow