JEROME M. FELDMAN, M.D., F.A.C.P.; JAMES W. PLONK, M.D.This content is PDF only. Please click on the PDF icon to access. Carcinoembryonic antigen is a cancer-specific antigen that is present in the plasma of 82% of patients with malignant tumors arising from structures of entodermal origin (1). The tumors include adenocarcinomas of the colon, stomach, pancreas, appendix, and gallbladder. Although carcinoid tumors are also found in the gastrointestinal tract, they have a neural crest (or neuroectodermal)rather than an entodermal origin (2). Six of seven children with neuroblastoma (a tumor of neural crest origin) had elevated plasma concentrations of carcinoembryonic antigen (1). It was therefore of interest to determine if patients with biopsy-proved metastatic carcinoid tumors had elevated plasma carcinoembryonic antigenFELDMAN JM, PLONK JW. Carcinoembryonic Antigen and Carcinoid Tumors. Ann Intern Med. 1975;83:82–83. doi: https://doi.org/10.7326/0003-4819-83-1-82_2Download citation file: Published: Ann Intern Med. 1975;83(1):82-83. Results provided by: Copyright © 2020 American College of Physicians. All Rights Reserved. Print ISSN: 0003-4819 | Online ISSN: 1539-3704Conditions of Use