(90)Y radioembolization (selective internal radiation therapy [SIRT]) is a valuable therapeutic option for unresectable hepatic metastases arising from primary colorectal cancer. The present study evaluated the prognostic value of (18)F-FDG PET/CT metabolic parameters for predicting survival after SIRT.
Methods: Eighty patients with hepatic metastases of colorectal cancer were treated with SIRT. (18)F-FDG PET/CT was performed at baseline and 3 mo after the treatment. Metabolic volume, total lesion glycolysis, and maximum and peak standardized uptake value (SUV(max) and SUV(peak), respectively) according to PET Response Criteria in Solid Tumors (PERCIST 1.0) were obtained from 3 liver lesions in each patient, and the corresponding percentage changes from baseline to follow-up were calculated. Tumor response was defined as more than a 30% decrease in these parameters. Furthermore, response was evaluated in accordance with Response Evaluation Criteria in Solid Tumors (RECIST 1.1). Toxicity events and survival were recorded.
Results: Overall median survival after SIRT was 60 wk. Responders who had a change in metabolic volume or total lesion glycolysis had significantly longer survival (92 vs. 49 wk [P = 0.006] and 91 vs. 48 wk [P = 0.025], respectively). However, neither RECIST 1.1 criteria nor changes in SUV(peak) or SUV(max) after treatment predicted outcome (P = 0.086 for RECIST; P = 0.310 for change in SUV(peak); P = 0.155 for change in SUV(max)).
Conclusion: Changes in metabolic volume and total lesion glycolytic rate as measured by (18)F-FDG PET predicted survival in patients with hepatic metastases from colorectal cancer, whereas changes in SUV(peak) or SUV(max) and RECIST 1.1 criteria did not predict survival.
Keywords: 18F-FDG PET; 90Y microspheres; SIRT; hepatic metastases; radioembolization.