消化管カルチノイド―機能面から

Carcinoid Tumor of the Gastrointestinal Tract: Its functional aspects

　カルチノイド腫瘍は，既に前世紀の初めからその存在が知られていたが，1907年Oberndorferにより通常の癌腫とは異なる性質を有するところから，カルチノイドなる名称が附された．その後，カルチノイド症候群と呼ばれる特徴的な症状を伴うことが知られ，それが本腫瘍の作るセロトニンとの関連において検討された．さらに本腫瘍は消化管のみならず，肺，胸腺，甲状腺，膵，卵巣および睾丸などからも生じ，かつセロトニン以外にも種々の活性物質を産生，放出することがわかって来た．

　以下，本稿においては，カルチノイド腫瘍が作る活性物質の生化学的，薬理学的性質に焦点をしぼり，本症の臨床像にふれつつ2，3の問題点を述べることにする．

　It has been known that, unlike usual gastrointestinal malignacies, carcinoid tumor is one of the functional or hormone-producing tumor. This paper reviewed such an interesting tumor from the points of biochemical, pharmacological background. Increased amounts of 5-HIAA, end metabolite of serotonin, in the urine confirm the diagnosis. However, there are many practical problems in this tumor. Wellknown carcinoid syndrome appears in only few cases, and thus the majority of the patients are overlooked when a suspicion is entertained on this syndrome. If the correct diagnosis is delayed, there is no chance of radical treatment because of extensive metastases. Evidences have now been accumulated that carcinoid tumor synthesizes and releases many kinds of active substances or hormones, beside serotonin, including histamine, bradykinin, prostaglandin, ACTH, MSH, ADH, PTH, insulin and various gastrointestinal polypeptide hormones. Recent studies have shown that among the enterochromaffin cells from that the carcinoid tumor arised there are some clusters of cells producing gastrointestinal hormones. New concepts of carcinoid spectrum, gastroenteropancreatic endocrine system, carcinoidislet cell tumor and apudoma, tumor originated from amine precussor uptake and decarboxylation system, have presented suggesting a possible interrelationship between cell origin of carcinoid tumor, these hormone production and clinical manifestations. However, little is known about these points because the tumor is relatively rare and the assay of above mentioned substances has not been easily available yet. For the early diagnosis and adequate therapy, further studies should be necessary.