Long-term clinical outcome of somatostatin analogues for treatment of progressive, metastatic, well-differentiated entero-pancreatic endocrine carcinoma

Background: Knowledge of factors able to predict the clinical outcome of homogenous series of entero-pancreatic endocrine tumours treated with somatostatin analogues is poor. This study was aimed at identifying predictors for efficacy of somatostatin analogues at inhibiting tumour growth and modifying patients' survival during long-term follow-up. Patients and methods: 31 patients with entero-pancreatic well-differentiated endocrine carcinoma received long-acting somatostatin analogues. All had progressive, metastatic disease (87% liver metastases, 38.7% distant extra-hepatic metastases). Results: Response rate after 6 months of treatment was 45.2% (all disease stabilisation: 27.8% of pancreatic vs. 81.8% of intestinal tumours, P = 0.007). The predictors for non-response were: pancreatic tumour (OR 5.8), no previous surgery (OR 6.7), and the presence of distant extra-hepatic metastases, the latter being also confirmed by multivariate analysis (OR 10.0). Responders maintained stabilisation for 26.5 months, and none died during follow-up. Different survival curves were observed for patients, responding at 6 months compared to non-responders (P = 0.004), 3-year survival rate being 100% and 52.3%, respectively. Conclusions: Distant extra-hepatic metastases are the major predictor of poor efficacy of somatostatin analogues in progressive, metastatic, well-differentiated entero-pancreatic endocrine carcinomas. Patients achieving response after 6 months of treatment, maintain it throughout a long-term follow-up. Non-responders after 6 months of treatment, have a worse survival, and should be considered for alternative treatments.