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 Ga-68-DOTANOC in patients affected by hepatic metastases from neuroendocrine tumours (NET) undergoing Y-90 radioembolization (Y-90-RE). Methods A group of 15 consecutive patients with unresectable NET liver metastases underwent Ga-68-DOTANOC PET at baseline and 6 weeks after Y-90-RE. Molecular response was defined as a reduction of >50 % in the tumour-to-spleen ratio (Delta T/S). The patients were divided into two groups (responders with Delta T/S >50 % and nonresponders with Delta T/S <50 %) Patients were followed up by imaging and laboratory tests every 3 months until death or for at least 36 months following Y-90-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 Ga-68-DOTANOC PET scans performed after Y-90-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 Ga-68-DOTANOC PET might be a useful predictor of survival in patients affected by NET liver metastases treated with Y-90-RE.