Abstract
Aim To evaluate the feasibility of early metabolic response assessment
with 18F-FDG PET/CT in patients with breast cancer liver metastases 4
weeks after radioembolization with Yttrium-90 labeled microspheres.
Methods 25 patients (mean age 58y, range 40–74) with advanced stage liver
metastases of breast cancer were treated with 1.9 ± 0.4 GBq of 90Y-microspheres
in the salvage setting and underwent 18F-FDG PET/CT at baseline and 4
weeks post-radioembolization. 14 patients (56 %) had an excessive hepatic tumor
burden (> 50 % of total liver volume), 21 patients (84 %) had extrahepatic
disease. Liver lesions with the highest SUVmax were selected as
target lesions and a cut-off was set at 50 % reduction to separate responders
from non-responders. The predictive impact of metabolic response on overall
survival (OS) was investigated along with other prognostic factors.
Results The median OS in this highly advanced metastatic cohort was 7
months (95 % CI, 5–9). All patients had a reduction in SUVmax (mean
ΔSUVmax: –49 ± 26 %) at 4 weeks post-treatment. Patients with
> 50 % SUVmax reduction survived longer (median OS 13 mo, 95 % CI
8–18) than the remaining patients (median OS 4 mo, 95 % CI 2–6; p = 0.001). From
all investigated baseline factors including age, performance status, and
presence of extra-hepatic disease, only the hepatic tumor burden had a
significant impact on OS (p = 0.02).
Conclusions This is the first preliminary evidence in breast cancer that
early post-radioembolization molecular response assessment of treated liver
metastases – as early as 4 weeks posttreatment – may predict survival. If
confirmed by larger series, FDG PET/CT could be considered for early
response-adapted treatment modifications.
Utility of 18F-FDG PET/CT for predicting pathologic complete response in hormone receptor-positive, HER2-negative breast cancer patients receiving neoadjuvant chemotherapy