Predictors of response to radio-embolization (TheraSphere (R)) treatment of neuroendocrine liver metastasis

Background: Neuroendocrine tumours (NET) frequently metastasize to the liver. NET liver metastasis has been shown to respond to Yttrium-90 microspheres therapy. The aims of the present study were to define factors that predict the response to radio-embolization in patients with NET liver metastases. Methods: From January 2006 until March 2009, all patients with NET liver metastasis that received radio-embolization using TheraSphere(R) (glass microspheres) were reviewed. The response was determined by a change in the percentage of necrosis (Delta N%) after the first radio-embolization based on the modified RECIST criteria (mRECIST) criteria. The following confounding variables were measured: age, gender, size of the lesions, liver involvement, World Health Organization (WHO) classification, the presence of extra-hepatic metastasis, octereotide treatment and previous operative [surgery and (RFA)] and non-operative treatments (chemo-embolization and bland-embolization). Results: In all, 25 patients were identified, with a median follow-up of 21.7 months. The median age was 64.6 years, 28% had extra-hepatic metastasis and 56% were WHO stage 2. Post-treatment, the mean Delta N% was 48.4%. Previous surgical therapy was a significant predictor of the response with a response rate of 66.7 Delta N% vs. 31.5 Delta N% (P = 0.02). Bilateral liver disease, a high percentage of liver involvement and large metastatic lesions were inversely related to the degree of tumour response although did not reach statistical significance. Conclusion: Radio-embolization increased the necrosis of NET liver metastasis mainly in patients with less bulky disease. This may imply that surgical therapy before radio-embolization would increase the response rates.