FDG PET/CT in the prediction of survival in patients after radioembolization of hepatic metastases from breast cancer

Objectives 90Yttrium (90Y) radioembolization (SIRT) has emerged as therapy for patients with hepatic metastases from breast cancer. In these patients we aimed to evaluate FDG PET/CT in the prediction of survival.

Methods Prior to SIRT, 45 patients underwent MAA-scintigraphy with SPECT(/CT) to quantify the liver-lung-shunt fraction and to determine the tumor-to-liver quotient (T/L). FDG PET/CT was performed at baseline and three months after SIRT, in order to calculate percentage changes in peak (ΔSUVmax) FDG uptake, relative to baseline. Treatment response at three months was assessed using contrast-enhanced CT. Follow-up examinations were available in 32 and survival data in all patients.

Results CT indicated partial response in 6/32 (19%) patients, stable disease in 21 (65%) and progressive disease in 5/32 (16%) patients. Overall mean survival after SIRT was 56 weeks. ΔSUVmax responder had a longer median survival of 60 weeks versus 43 weeks in non-responder, though this difference was not significant (P=0.15). However, in patients with estrogen receptor positive cancer, responder had a significant longer median survival (60 weeks) compared to non-responder (39 weeks; P<0.05). Also in progesterone receptor positive responder a significant longer survival (74 weeks) was found compared to non-responder (39 weeks; P<0.05). Pre-therapeutic MAA-scintigraphy (T/L>1.5: survival 43 weeks, T/L<1.5: survival 52 weeks; P=0.25) as well as CT (P=0.42) were not predictive for survival. Presence of extra-hepatic metastases was associated with shorter survival time (mean survival 52 weeks versus 78 weeks; P=0.16).

Conclusions Response assessed with FDG PET/CT at three months after radioembolization was able to predict patient survival in women suffering from estrogen and progesterone receptor positive breast cancer. Uptake on MAA scintigraphy as well as CT response criteria were not predictive for survival