Antiproliferative Systemic Therapies for Metastatic Small Bowel Neuroendocrine Tumours

Neuroendocrine neoplasms (NENs) are a heterogeneous group of malignancies with rising incidence and prevalence. Outcome and therapy of small bowel neuroendocrine tumours (SBNETs) is variable, depending on the grade, differentiation, tumour burden, as well as the site of the tumour origin. Because of this, multidisciplinary approach is essential. Large randomized clinical trials, with somatostatin analogues (PROMID, CLARINET) or with peptide receptor radionuclide therapy (PRRT) with 177-lutetium (NETTER-1 trial) as well as the mammalian target of rapamycin inhibitor (mTOR) everolimus (RADIANT trials), represent milestones for the medical management of unresectable grade 1 and 2 SBNETS over the last decade. Novel therapies, such as tyrosine kinase inhibitors (TKI), are on the cutting edge. However, multiple unsolved questions remain. This review provides a comprehensive review of the main systemic therapeutic options for advanced SBNETs and discusses the latest guideline recommendations for palliative treatment.