Purpose: Functional tumor volume (FTV) and total lesion glycolysis (TLG) are measures of metabolic activity of tumors determined by fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT images. These parameters could potentially have clinical value in response to treatment evaluation and disease prognostication. The objectives of this study were to investigate the relationship between functional tumor parameters (FTV and TLG) and clinical outcomes in patients with colorectal cancer liver metastases (CRCLM) undergoing (90)Y-resin microsphere selective internal radiation therapy (SIRT) (SIR-Spheres®, Sirtex Medical Limited, Lane Cove, NSW, Australia).
Methods: FDG PET/CT studies of 20 patients with unresectable CRCLM who underwent (90)Y SIRT under a phase II clinical trial were analyzed. FTV and TLG were calculated using PET VCAR (GE Healthcare, Milwaukee, WI, USA) on pretreatment and 4-week posttreatment scans. The effects of pretreatment and posttreatment functional tumor activity on patient survival were evaluated using Kaplan-Meier survival curves.
Results: The median survival in the study group was 14.8 months (range 2.0-27.7 months). The median survival for patients with pretreatment FTV values of above and below 200 cc were 11.2 and 26.9 months, respectively (p < 0.05). The median survival for patients with 4-week posttreatment FTV values of above and below 30 cc were 10.9 and 26.9 months, respectively (p < 0.05). The median survival for patients with pretreatment TLG values of above and below 600 g were 11.2 and 26.9 months, respectively (p < 0.05). The median survival for patients with 4-week posttreatment TLG values of above and below 100 g were 10.9 and 26.9 months, respectively (p < 0.05).
Conclusion: Pretreatment and posttreatment FTV and TLG showed very strong association with survival. These values can be useful quantitative criteria for patient selection and disease prognostication when (90)Y SIRT is contemplated in patients with CRCLM.