PET/CT Imaging Characteristics After Radioembolization of Hepatic Metastasis from Breast Cancer

To define positron emission tomography/computed tomography (PET/CT) imaging characteristics during follow-up of patients with metastatic breast cancer (MBC) treated with yttrium-90 (Y90) radioembolization (RE). From January 2011 to October 2017, 30 MBC patients underwent 38 Y90 glass or resin RE treatments. Pre-RE PET/CT was performed on average 51 days before RE. There were 68 PET/CTs performed after treatment. Response was assessed using modified PERCIST criteria focusing on the hepatic territory treated with RE, normalizing SUVpeak to the mean SUV of liver uninvolved by tumor. An objective response (OR) was defined as a decrease in SUVpeak by at least 30%. Of the 68 post-RE scans, 6 were performed at 0–30 days, 15 at 31–60 days, 9 at 61–90 days, 13 at 91–120 days, 14 scans at 121–180 days, and 11 scans at > 180 days after RE. Of the 30 patients, 25 (83%) achieved OR on at least one follow-up. Median survival was 15 months after the first RE administration. Highest response rates occurred at 30–90 days, with over 75% of cases demonstrating OR at that time. After 180 days, OR was seen in only 25%. There was a median TTP of 169 days among responders. In MBC, follow-up PET/CT after RE demonstrates optimal response rates at 30–90 days, with progression noted after 180 days. These results help to guide the timing of imaging and also to inform patients of expected outcomes after RE.