Outcomes Following Observation of Small Non-Functioning Neuroendocrine Tumors of the Pancreas. Data from the Registry of the Loginov Moscow Clinical Scientific Center

Aim: to evaluate results of follow-up of patients with pancreatic non-functioning neuroendocrine tumors of the stage T1–T2 using a medical registry.

Materials and methods. A retrospective analysis of the medical registry data of the Loginov Moscow Scientific Center was conducted, which included 312 patients with pancreatic neuroendocrine tumors from 2014 to 2023. Observation was recommended for 115 (36.9 %) patients. The inclusion criteria: diagnosis of pancreatic neuroendocrine tumor; non-functioning tumor status; asymptomatic disease; tumor size less than 3 cm; patient’s consent. The exclusion criteria were patient’s refusal of observation; tumor growth of more than 3 mm/year of observation; appearance of disease symptoms. Based on the registry data, gender and age of patients, size and location of tumors, TNM stage, tumor growth dynamics (mm/year), biochemical markers of neuroendocrine tumors, and the presence of concomitant pathology were studied. Whole genome sequencing was performed on 53 patients with first diagnosed pancreatic neuroendocrine tumors.

Results. Six patients (5.2 %) were excluded from the study: three refused to be observed, three demonstrated tumor growth. 109 patients diagnosed with non-functioning pancreatic neuroendocrine tumor were included in the analysis: 78 (71.6 %) women and 31 (28.4 %) men aged from 22 to 86 years (58.5 ± 10.8 years) at the time of presentation. The median follow-up time was 34.0 (2.0–86.0) months. The most common location of tumors was in the head of the pancreas — 45.5 % (n = 51). Of the 109 patients observed, 103 were diagnosed with stage T1 tumors (94.5 %), 6 — with T2 (5.5 %). The average tumor size was 11.9 ± 3.8 mm (3.1–29.0 mm) (n = 118). An increase in biochemical markers of neuroendocrine tumors (gastrin, chromogranin A) was associated with atrophic gastritis. Germline mutations were detected in 24.0 % of patients (n = 12). The most common mutations in the sample were the CHEK2 gene (n = 4).

Conclusions. According to the registry data, active observation is an acceptable tactic for managing patients with T1 non-functioning pancreatic neuroendocrine tumors. Likely it is not the size of the tumor but its growth rate that has prognostic significance, and therefore a protocol for monitoring this group of patients is required. The effect of estrogens on tumor growth inhibition and the role of CHEK2 gene mutations are perspectives for future research.

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