Objective : To determine predictors of survival after Yttrium-90 (Y90) radioembolization of chemo-refractory hepatic metastases from breast cancer.
Methods : In an institutional review board approved retrospective study, patients with chemo-refractory hepatic metastases from breast cancer who underwent Y90 radioembolization from 2013 to 2018 were evaluated. Patients were analyzed using age, menopausal status, sites of metastasis, date of the hepatic metastasis diagnosis, date of radioembolization procedure, pre- and post-Y90 imaging, presence of abdominal pain, encephalopathy and/or ascites prior to or after radioembolization, and relevant version 5 Common Terminology Criteria for Adverse Events (CTCAE) at 1 and 3 months post-Y90 treatment. Overall survival (OS) from first Y90 therapy was estimated using Kaplan-Meier estimation, and predictors of survival were analyzed using log-rank analysis. Statistical analysis was performed using SPSS Version 25 (IBM corporation, Armonk, NY).
Results : Overall, 24 patients with chemo-refractory metastatic breast cancer were included. The median number of failed chemotherapy lines in each patient was 2. All patients (100%) were female with the median age of 57 years. The median OS from first Y90 treatment was 35.4 months, and the median OS from time of hepatic metastases diagnosis was 48.6 months. The median follow-up period was 22.3 months. Y90 radioembolization within 6 months of hepatic metastases diagnosis was a significant positive predictor of survival with median OS of 38.9 months vs. 22.1 months for those undergoing Y90 > 6 months after hepatic metastases diagnosis (p=0.033). Estrogen receptor (ER) positive status was a predictor of prolonged survival (median OS of 38.6 months for ER+ vs. 5.4 months for ER- (p=0.005)). The presence of baseline abdominal pain was a predictor of poor survival with median OS of 12.8 months vs. 38.6 months for those with no abdominal pain (p<0.001). Additionally, the presence of baseline ascites was also a significant negative predictor of OS of 1.7 months vs. 35.4 months for others (p=0.037). A CTCAE grade ≥ 2 at 1 and 3 months were both significant predictors of poor survival. Median OS for those with CTCAE grade ≥ 2 toxicity at 1 month was 5.4 months vs. 35.4 months for others (p=0.046). Similarly, median OS for patients with CTCAE grade ≥ 2 at 3 months was 5.4 months vs. 38.6 months for others (p=0.017). Age, menopausal status, post-Y90 image response, progesterone receptor and HER2 status, and baseline functional status were not found to be predictors of OS.
Conclusions : The results of this study suggest that in chemo-refractory breast cancer, Y90 radioembolization within 6 months of diagnosis of hepatic metastases, and ER+ status are predictors of prolonged survival. Conversely, baseline abdominal pain, ascites, and CTCAE grade 2 or higher at 1 and 3 months post-Y90 are significant negative predictors of overall survival.