Neuroendocrine neoplasms of the small intestine and the appendix — update of the diagnostic and therapeutic guidelines (recommended by the Polish Network of Neuroendocrine Tumours) [Nowotwory neuroendokrynne jelita cienkiego i wyrostka robaczkowego — uaktualnione zasady diagnostyki i leczenia (rekomendowane przez Polską Sieć Guzów Neuroendokrynnych)]

Updated Polish recommendations for the management of patients with neuroendocrine neoplasms (NENs) of the small intestine (SINENs) and of the appendix (ANENs) are presented here. The small intestine, and especially the ileum, is one of the most common locations for these neoplasms. Most of them are well-differentiated and slow-growing tumours; uncommonly - neuroendocrine carcinomas. Their symptoms may be untypical and their diagnosis may be delayed or accidental. Najczęściej pierwszą manifestacją ANEN jest jego ostre zapalenie. Typical symptoms of carcinoid syndrome occur in approximately 20–30% of SINENs patients with distant metastases. In laboratory diagnostics the assessment of 5-hydroxyindoleacetic acid concentration is helpful in the diagnosis of carcinoid syndrome. The most commonly used imaging methods are ultrasound examination, computed tomography, magnetic resonance imaging, colonoscopy and somatostatin receptor imaging. Histopathological examination is crucial for the proper diagnosis and treatment of patients with SINENs and ANENs. The treatment of choice is a surgical procedure, either radical or palliative. Long-acting somatostatin analogues (SSAs) are essential in the medical treatment of functional and non-functional SINENs. In patients with SINENs, at the stage dissemination with progression during SSAs treatment, with high expression of somatostatin receptors, radioisotope therapy should be considered first followed by targeted therapies — everolimus. After the exhaustion of the above available therapies, chemotherapy may be considered in selected cases. Recommendations for patient monitoring are also presented.