Background

There are only few, but controversial data on the prognostic role of upfront primary tumor resection and mesenteric lymph node dissection (PTR) in patients with diffuse metastasized small intestinal neuroendocrine neoplasia (SI-NEN). Therefore, the prognostic role of PTR and other factors was determined in this setting.

Methods

This retrospective cohort study included patients with stage IV SI-NETs with unresectable distant metastases without clinical and radiological signs of acute bowel obstruction or ischemia. Patients diagnosed from January 2002 to May 2020 were retrieved from a prospective SI-NEN database. Disease specific overall survival (OS) was analyzed with regard to upfront PTR and a variety of other clinical (e.g. gender, age, Hedinger disease, carcinoid syndrome, diarrhea, laboratory parameters, metastatic liver burden, extrahepatic and extra-abdominal metastasis) and pathological (e.g. grading, mesenteric gathering) parameters by uni- and multivariate analysis.

Results

138 patients (60 females, 43.5%) with a median age of 60 years, of whom 101 (73%) underwent PTR and 37 (27%) did not, were included in the analysis. Median OS was 106 (95%CI 72.52-139.48) months in the PTR group and 52 (95%CI 30.55-73.46) in the non-PTR group (p=0.024), but the non-PTR group had more advanced metastatic disease (metastatic liver burden ≥50% 32.4% vs. 13.9%). There was no significant difference between groups regarding the rate of surgery for bowel complications during a median follow-up of 51 months (PTR group 10.9% and non-PTR group 16.2%, p=0.403). Multivariate analysis revealed age <60 years, normal C-reactive protein (CRP) at baseline, absence of diarrhea, less than 50% of metastatic liver burden, and treatment with PRRT as independent positive prognostic factors, whereas PTR showed a strong tendency towards better OS, but level of significance was missed (p=0.067). However, patients who underwent both, PTR and peptide radioreceptor therapy (PRRT) had the best survival compared to the rest (137 vs. 73 months, p=0.013).

Conclusions

PTR in combination with PRRT significantly prolongs survival in patients with stage IV SI-NEN. Prophylactic PTR does also not result in a lower reoperation rate compared to the non-PTR approach regarding bowel complications.