Relationship of radiation dose to efficacy of radioembolization of liver metastasis from breast cancer.

PURPOSE: To determine the relationship of tumoral and nontumoral radiation dose to response and toxicity after transarterial radioembolization (TARE) of breast cancer liver metastasis.

METHODS

This retrospective study evaluated all patients with breast cancer liver metastases treated with TARE (2/2011-6/2019). Extent of disease was measured as unilobar or bilobar on baseline PET/CT prior to TARE. Response was assessed for targeted regions with modified PERCIST criteria on first follow-up PET/CT. Tumoral and nontumoral liver dosimetry was evaluated by performing volumetric segmentation on post-TARE Bremsstrahlung SPECT/CT. ≥Grade 3 hepatotoxicity was defined as ≥grade 3 bilirubin/AST/ALT elevation or ascites requiring intervention. Fisher's exact tests, Wilcoxon rank sum tests, and Kaplan-Meier survival analysis were performed.

RESULTS

Among 64 women, 60 patients had pre- and post-TARE PET/CT, of whom 46/60 (77 %) achieved objective response (OR). Responders received higher tumoral dose with a median (interquartile range) of 167 (96-217) vs. 54 (45-62) Gy (p < 0.001). ≥Grade 3 hepatotoxicity occurred in 8/64 (12.5 %) and was associated with higher pre-treatment bilirubin levels of 0.9 (0.9-1.1) vs. 0.5 (0.4-0.7) mg/dL (p = 0.013). Median overall survival (OS) was 11 (95 % CI 10-19) months. Bilobar disease (Hazard Ratio [HR]: 2.77, 95 % CI 1.11-6.89, p = 0.028) and elevated pre-TARE AST (HR 1.02, 95 % CI 1.01-1.03, p < 0.001) were independently associated with shorter survival. ≥Grade 3 hepatotoxicity was associated with reduced survival (p < 0.001). OR was associated with longer OS of 17 months, compared with 10 months (p = 0.027).

CONCLUSION

In TARE for breast cancer liver metastasis, higher tumoral radiation dose (>79.5 Gy) was associated with OR, which was associated with longer survival. Pre-existing liver dysfunction was associated with hepatotoxicity, which was associated with decreased survival.