Evaluation of (177)Lu-Dotatate treatment in patients with metastatic neuroendocrine tumors and prognostic factors

BACKGROUND: (177)Lu peptide receptor radionuclide therapy (PRRT) is a recently approved therapy in Spain that has been demonstrated to be a well-tolerated therapy for positive somatostatin receptor advanced gastroenteropancreatic neuroendocrine tumors. AIM: To determine the impact of PRRT on quality of life, radiologic and metabolic response, overall survival, prognostic factors and toxicity. METHODS: Thirty-six patients treated with (177)Lu-PRRT from 2016 to 2019 were included. The most frequent location of the primary tumor was the gastrointestinal tract (52.8%), pancreas (27.8%), and nongastropancreatic neuroendocrine tumor (11.1%). The liver was the most common site of metastasis (91.7%), followed by distant nodes (50.0%), bone (27.8%), peritoneum (25.0%) and lung (11.1%). Toxicity was evaluated after the administration of each dose. Treatment efficacy was evaluated by two parameters: stable disease and disease progression in response evaluation criteria in solid tumors 1.1 criterion and prognostic factors were tested. RESULTS: From 36 patients, 55.6% were men, with a median age of 61.1 ± 11.8 years. Regarding previous treatments, 55.6% of patients underwent surgery of the primary tumor, 100% of patients were treated with long-acting somatostatin analogues, 66.7% of patients were treated with everolimus, 27.8% of patients were treated with tyrosine kinase inhibitor, and 27.8% of patients were treated with interferon. One patient received radioembolization, three patients received chemoembolization, six patients received chemotherapy. Hematological toxicity was registered in 14 patients (G1-G2: 55.5% and G3: 3.1%). Other events presented were intestinal suboclusion in 4 cases, cholestasis in 2 cases and carcinoid crisis in 1 case. The median follow-up time was 3 years. Currently, 24 patients completed treatment. Nineteen are alive with stable disease, two have disease progression, eight have died, and nine are still receiving treatment. The median overall survival was 12.5 mo (95% confidence interval range: 9.8–15.2), being inversely proportional to toxicity in previous treatments (P < 0.02), tumor grade (P < 0.01) and the presence of bone lesions (P = 0.009) and directly proportional with matching lesion findings between Octreoscan and computed tomography pre-PRRT (P < 0.01), , primary tumor surgery (P = 0.03) and metastasis surgery (P = 0.045). In a multivariate Cox regression analysis, a high Ki67 index (P = 0.003), a mismatch in the lesion findings between Octreoscan and computed tomography pre-PRRT (P < 0.01) and a preceding toxicity in previous treatments (P < 0.05) were risk factors to overall survival. CONCLUSION: Overall survival was inversely proportional to previous toxicity, tumor grade and the presence of bone metastasis and directly proportional to matching lesion findings between Octreoscan and computed tomography pre-PRRT and primary tumor and metastasis surgery.