Endocrine Abstracts

Introduction: Neuroendocrine tumors (NET) represent a heterogeneous group of tumors with different locations, whose management is based on the pathology, immunohistochemical, genetic and molecular profile.

Materials and method: We followed 8 patients with NET between 2014 and 2022 registered at the “C.I. Parhon” National Institute of Endocrinology, Bucharest, who benefited from peptide receptor radionuclide therapy (PRRT). Among them, 75% were male with the average age at diagnosis 43.37±7.15 years. According to the WHO 2019 classification, 1 case presented a well-differentiated tumor grade G1, 5 cases G2, 1 case associated 2 tumors with grade G1+G2 and 1 case pancreatic mixed neuroendocrine–nonneuroendocrine neoplasms (MiNEN).

Results: The primary localization was in 6 cases pancreatic, one bronchial and pancreatic, one ileo-cecal. All patients presented secondary determinations at diagnosis, 50% hepatic, 42% lymphnodal and 8% vertebral. Sporadic forms were in 6/8 cases and 2/8 cases presented MEN1 syndrome, in one case having confirmed the heterozygous deletion of the MEN1 gene (c.928-33_963del). At diagnosis, carcinoid syndrome was present in 6/8 cases and the average of chromogranin values in 5/8 cases being 1236.4±881.2 ng/ml. In 3 patients, the presence of somatostatin receptors was evaluated: SSTR2 positive, moderate expression in 2/3, respectively strong expression in 1/3, and SSTR5 negative in 1/3, positive with weak expression in 1/3 and moderate expression in 1/3 cases. Six cases presented progressive disease before the initiation of PRRT treatment and the average interval from diagnosis to PRRT was 16.62±14.27 months. The patients performed between 2 and 6 cycles with an average of 3.37 cycles, the radionuclides used was: (177)Lu-DOTATOC (average cumulative dose(ACD)=16.5 GBq), (90)Y-DOTATOC (ACD=10.57 GBq) and (225) Ac-DOTATOC (ACD=20.5 MBq). The treatment associated with PRRT was: somatostatin analogs (87.5%), surgery (75%), chemotherapy (25%), chemoembolization (12.5%). PRRT was never used as the first line of treatment. Regarding the evolution of the disease according to the RECIST1.1 criteria determined over a period of 6 months after the end of the treatment, 50% presented a partial response, 37.5% stable disease, respectively 12.5% (1 case) progressive disease, the case being represented by the tumor MiNEN, where the death also occurred. Neuroendocrine tumor marker Cromogranine A decreased from the average of 1236.4±881.2 ng/ml before PRRT, at 200.2±188.4 ng/ml, at approximately 4.8 months after the last PRRT session.

Conclusions: PRRT shows benefits in the case of well-differentiated neuroendocrine tumors grade G1-G2, with bronchial or gastroenteropancreatic localization, and remains controversial in the case of poorly differentiated tumors, respectively MiNEN.