¹⁸F-FDG PET/CT Predicts Survival After Radioembolization of Hepatic Metastases from Breast Cancer

Abstract

⁹⁰Y radioembolization (selective internal radiation therapy [SIRT]) has emerged as a valuable therapeutic option in unresectable, chemotherapy-refractory hepatic metastases from breast cancer. The objective of the present study was to evaluate ¹⁸F-FDG PET/CT for predicting survival in these patients. Methods: Fifty-eight consecutive patients with hepatic metastases from breast cancer were treated with SIRT. Before therapy, all patients underwent MRI of the liver. ¹⁸F-FDG PET/CT was performed at baseline and 3 mo after SIRT to calculate percentage changes in maximum ¹⁸F-FDG standardized uptake value (SUV_max) relative to baseline. A decrease of more than 30% in the follow-up scan, compared with the baseline examination, indicated therapy response. Treatment response at 3 mo was also assessed in 43 patients using contrast-enhanced MRI and CT on the basis of the Response Evaluation Criteria in Solid Tumors. All patients were followed to complete survival data. Results: Overall median survival after SIRT was 47 wk. Response as assessed with SUV_max correlated significantly with survival after radioembolization, with responders having significantly longer survival (65 wk) than nonresponders (43 wk; P < 0.05). In multivariate analysis the change in SUV_max was identified as the only independent predictor of survival (hazard ratio, 0.23; P < 0.005). Furthermore, a high pretherapeutic SUV_max (>20) was associated with a significantly shorter median survival than was an SUV_max of 20 or less (21 vs. 52 wk; P < 0.005). The presence of extrahepatic metastases (mean survival in both groups, 47 wk; P = 0.92), hormone receptor status (estrogen, P = 0.53; progesterone, P = 0.79; Her-2/neu, P = 0.49), and MRI/CT response (P = 0.91) did not predict survival. Conclusion: The change in SUV_max as assessed by ¹⁸F-FDG PET/CT before and 3 mo after SIRT was identified as the only independent predictor of survival in patients with hepatic metastases of breast cancer.