Selective Internal Radiation Therapy (Sirt) For Treatment Of Patients With Breast Cancer With Metastatic Liver Disease

1135 Background: Selective internal radiation therapy (SIRT) has become a treatment option as salvage therapy for liver-dominant metastasis which is also used in patients (pts) with breast cancer. It is based on hepatic arterial infusion of resin microspheres containing the pure ß-emitter Yttrium-90. The goal of this cohort analysis was evaluate the clinical efficacy of SIRT and to define biomarkers predicting response to this new option. Methods: We retrospectively analyzed data from 40 pts with breast cancer (39 female, 1 male) at a median age of 60.3 yrs (31-73 yrs) who had received SIRT for metastatic liver disease from 2002-2009. We used survival analysis techniques (Kaplan-Meier estimator and Cox regression models) for this exploratory study. Results: 13 pts (33.3%) were premenopausal, 23 (59.0%) postmenopausal, and 3 (7.7%) perimenopausal; 14 pts (36.8%) overexpressed HER2/neu; 27 pts (71.1%) were hormone receptor positive; 39 pts (97.5%) had received previous chemotherapy for metastatic disease, 34 (87.2%) hormone therapy. 37 pts (94.9%) had received anthracyclines, and 34 (89.5%) taxanes before SIRT. Median time from diagnosis of breast cancer to SIRT was 6.8 yrs (1.1-27.3 yrs). In 19 pts (47.5%), metastasis was limited to the liver, 21 (52.5%) pts had liver-predominant metastasis (21 bone, 7 non-regional lymph nodes, 4 lung, 5 others). Overall response rate (ORR) in the liver was 45.5% (95% CI: 0.29-0.62). Stable disease for more than 8 weeks was achieved in 12.1% of pts. Median PFS in the liver was 3.3 mo (1.8-32.8 mo), and median TTP 3.5 mo (1.8-32.8 mo). Median overall survival (OS) was 8.2 mo. Bivariate Cox regression models (using the Wald test) for baseline biomarkers before SIRT revealed a significant correlation of CEA (p=0.022), CA 15-3 (p=0.006), and LDH (p=0.012) with OS. No correlation was observed for C-reactive protein levels (p=0.74). Conclusions: This analysis of SIRT applied in breast cancer pts with metastatic liver disease indicates substantial clinical activity of this treatment option in highly pretreated breast cancer pts. CEA, CA 15-3, and LDH baseline levels in serum before SIRT appear to be predictors for OS. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration SIRTEX