Approximately 10–15% of patients with midgut carcinoids suffer from watery diarrhea, flushing, right-sided heart failure, and bronchial constriction (carcinoid syndrome), due to the tumor hypersecretion of a variety of endocrine substances, the most frequent of which are serotonin (5-hydroxytryptamine) and the tachykinins (38, 39), and therefore SST analogs are important palliative tools for these patients. This evidence concerns the gene SST and carcinoid syndrome.