Carcinoid tumors of the gut: Diagnosis and treatment

Carcinoids are relatively uncommon tumors, which may occur anywhere along the gastrointestinal tract. The appendiceal carcinoid is in autopsy series the most prevalent, but frequently overlooked clinically unless routinely searched for at appendectomy. In the stomach and the rectum the carcinoids often present as simple benign polypous lesions, fortuitously discovered during endoscopy, while the rare colon carcinoid is generally a large, bulky tumor at time of diagnosis. The mid-gut carcinoid is most frequently located in the terminal ileum and tends to prevail in clinical series due to its common association with the carcinoid syndrome. Ventricular, rectal and appendiceal carcinoids are generally benign and the extent of surgery may safely be based on the size of the tumor. Local excision or simple appendectomy is thus generally sufficient and only the larger, invasive or clearly malignant lesions require more extensive surgery. The mid-gut carcinoids on the other hand are frequently malignant, irrespective of tumor size, and surgery should carefully aim to remove mesenteric metastases together with the primary tumor. Also in cases with disseminated mid-gut carcinoids tumor debulking of the larger mesenteric and liver metastases may cause considerable alleviation of symptoms and probably facilitates medical treatment of the carcinoid syndrome. Surgery may also relieve abdominal symptoms due to intestinal entrapment or impaired intestinal circulation, which is frequently encountered in association with the more advanced mid-gut carcinoid.