Molecular response assessed by 68Ga-DOTANOC and survival after 90Y microsphere therapy in patients with liver metastases from neuroendocrine tumours

PURPOSE: We investigated the prognostic role of 68Ga-DOTANOC in patients affected by hepatic metastases from neuroendocrine tumours (NET) undergoing 90Y radioembolization (90Y-RE). METHODS: A group of 15 consecutive patients with unresectable NET liver metastases underwent 68Ga-DOTANOC PET at baseline and 6 weeks after 90Y-RE. Molecular response was defined as a reduction of >50 % in the tumour-to-spleen ratio (ΔT/S). The patients were divided into two groups (responders with ΔT/S >50 % and nonresponders with ΔT/S <50 %) Patients were followed up by imaging and laboratory tests every 3 months until death or for at least 36 months following 90Y-RE. Statistical analysis was performed to identify factors predicting overall survival (OS) and progression-free survival (PFS). RESULTS: A decrease in T/S ratio was seen in all patients on 68Ga-DOTANOC PET scans performed after 90Y-RE. Nine patients were classified as responders and six as nonresponders. The mean OS in all patients was 31.0 months. Responders had a significantly (p < 0.001) longer OS (mean 36.0 ± 2.5 months) and PFS (mean 29.7 ± 3.4 months) than nonresponders. In a multivariate analysis, none of the other examined variables including age, unilobar vs. bilobar locations, bilirubin levels, radiological response or the presence of extrahepatic disease significantly predicted patient outcome. CONCLUSION: Molecular response assessed with 68Ga-DOTANOC PET might be a useful predictor of survival in patients affected by NET liver metastases treated with 90Y-RE.