Developments in diagnosis and treatment of metastatic midgut carcinoid tumors. A review

Carcinoids are neuroendocrine tumours derived from enterochromaffin cells which are widely distributed in the body and may, therefore, arise from any site. They are traditionally described as originating from the foregut, midgut and hindgut. Localisation in the gastrointestinal tract is the most frequent, among which the appendiceal involvement is often found at laparoscopy for appendicitis and the small bowel is known for the liver metastases with the production of serotonin causing the characteristic carcinoid syndrome with diarrhoea and flushes. The overall incidence of carcinoid disease has increased in the past decades, but whether this is a true increase or due to early detection or better recognition at pathology is not known. The prognosis of metastatic carcinoid tumours has improved during the last decade resulting in a 5 year survival of approximately 50% in the Netherlands. Due to a longer survival, complications such as carcinoid heart disease and new metastatic patterns like skin and bone metastases may become a more important feature in carcinoid disease. New developments are in the field of diagnostics (fine-tuning of the pathology, videocapsule endoscopy to find the primary tumour, positron emission tomography [PET] scanning) and treatment options (radiofrequency ablation, radioactive octreotide, meta-iodobenzylguanidine combinations). The new serum marker of carcinoid, chromogranin A, may play an important role in the follow-up and NT-proBNP for the detection of heart problems. Combining new diagnostic and treatment modalities in metastatic carcinoid patients may result in a better quality of life and a longer survival. The increasing number of therapeutic options and diagnostic procedures requires a multidisciplinary approach focused on tailor-made therapy based on patients' specific conditions preferably in specialised centres and in clinical studies.