Gastric carcinoids and their precursor lesions: a histologic and immunohistochemical study of 23 cases

Article Abstract:

Carcinoids are tumors usually associated with the gastrointestinal tract, although similar lesions may occur in the bronchial tubes of the lungs as well. Carcinoids were given their name at a time when it was believed that they could not metastasize, but now it is recognized that these tumors are, in some cases, capable of metastatic spread. Older pathology books state that carcinoids of the stomach comprise no more than five percent of all carcinoids of the gastrointestinal tract. However, the widespread use of endoscopy has led to the recognition that gastric carcinoids are, in fact, far more common than previously suspected and may actually comprise one-third of all gastrointestinal carcinoids. Several conditions confer high risk for the development of gastric carcinoids. Among these is pernicious anemia; up to nine percent of all pernicious anemia patients may have gastric carcinoids. These tumors are also likely in patients taking inhibitors of gastric secretion for Zollinger-Ellison syndrome, which is associated with secreting pancreatic tumors. Hypergastrinemic chronic atrophic gastritis type A is also associated with the development of gastric carcinoids. There is evidence that in all these conditions, the trophic effect of excess gastrin contributes to the development and growth of the carcinoid. In such cases, surgical removal of the antrum of the stomach, where the gastrin-secreting cells are located, may result in the regression of the carcinoids, and be preferable to removal of most, or all, of the stomach. A histopathological study of 23 gastric carcinoids was conducted, and it was found that in 19 cases the syndrome was associated with hypergastrinemic chronic atrophic gastritis type A. Such patients would be good candidates for the less aggressive surgical approach of antral resection. The remaining four carcinoids, however, showed histological signs of being more aggressive, and signs of hypertrophy of gastrin-secreting cells were not found in these specimens. These four carcinoids, therefore, would not have been expected to respond to antrectomy, and aggressive surgical treatment would be advisable. (Consumer Summary produced by Reliance Medical Information, Inc.)

Complications and side effects, Risk factors, Development and progression, Stomach cancer, Carcinoid, Carcinoid tumor, Gastritis, Gastrointestinal tumors

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An analysis of immunocomplexes for the detection of the early stages of colon cancer

Article Abstract:

Considerable evidence has accumulated that many cancer patients have relatively high levels of circulating immune complexes. The notion is that the immune system is reacting to the presence of a tumor by forming antibodies, but these antibodies are inadequate to completely destroy the tumor. Nonetheless, either through the destruction of a few cells, or the shedding of some tumor antigens, some specific tumor antigens end up circulating in the bloodstream complexed with the anti-tumor antibodies. Although immune complexes may arise from many other processes besides tumor growth, it is sometimes possible to remove immune complexes from the blood and use immunological techniques to identify the specific antigen trapped within. For developing such a method, which might serve as a useful early detection system for colon cancer, proteins were obtained from a line of human colon cancer cells. These proteins were then injected into bunnies. The tumor antigens are sufficiently foreign to the rabbit that copious amounts of antibodies are made, which may be purified from small samples of the rabbit's blood. These antibodies are then chemically labelled with radioactive iodine-125. A sample of human immune complexes extracted from blood may then be tested with this radiolabeled antibody. If the radiolabeled rabbit antibody recognizes the antigen within the immune complexes, it too will bind, and the entire complex will now be radioactive in direct proportion to the amount of rabbit antibody bound. When this antibody test was used on patients known to have Duke's stage A colon cancer, 50 percent were positive. For stage B patients, 88 percent were positive. Less binding was seen in more advanced cancer patients, presumably due to the generally decreased immune complexes observed in these cases. The test was negative for patients with stomach cancer and inflammatory bowel disease, and only 10 percent of patients with pancreatic or breast cancer were positive by this assay. These preliminary results suggest that the immune assay may provide a useful method for the detection of early colon cancer. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Usage, Diagnosis, Colorectal cancer, Immune complexes, Immunoassay, Tumor antigens

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