Tissue carcinoembryonic antigen and DNA aneuploidy in precancerous and cancerous colorectal lesions

Article Abstract:

Carcinoembryonic antigen (CEA) is the most widely studied tumor marker; CEA is an antigen that is preferentially associated with transformed tumor or cancer cells. Most of the clinical research on CEA, however, has focused on its use in monitoring the possible recurrence of cancer in patients who have had tumors removed. Likewise, although DNA ploidy (the number of chromosome sets in a cell) has been widely studied, most analyses focus on histopathologic properties of well-recognized tumors. In this study, CEA and DNA ploidy were used to examine precancerous conditions, in particular inflammatory bowel disease and colorectal adenoma (a tumor), to determine if these factors may be of value in predicting which patients are at highest risk for developing cancer. The biochemical assay for CEA found both inflammatory bowel tissue and colorectal adenoma had higher levels of CEA than normal tissue. The levels of CEA found in actual colorectal cancer were even higher. DNA ploidy was estimated by measuring the DNA content of cancer cells by using flow cytometry, in which cells are individually dropped through a counting device after having been fluorescently stained for DNA. Normal tissue has a DNA content which reflects a normal, or diploid, chromosome content. About 31.6 percent of the inflammatory bowel specimens had DNA contents suggestive of an abnormal, aneuploid, chromosome content. About 10.5 percent of the adenomas were aneuploid, as were 51.6 percent of the actual colorectal carcinomas. In general, aneuploid growths tended to have a higher concentration of CEA than did their diploid counterparts. Unfortunately, in this study it was not possible to tell if the precancerous growths with aneuploid chromosome content and increased CEA have a greater likelihood of malignant transformation. Nonetheless, it is clear that the precancerous conditions are intermediate between normal tissue and cancerous tissue in their quantities of CEA. The wide variability in the amount of CEA produced by any single tumor may preclude its use as an accurate prognostic tool. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Usage, Flow cytometry, Ploidy, Chromosome numbers

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Usefulness of serum glycoconjugates in precancerous and cancerous diseases of the oral cavity

Article Abstract:

Cancerous cells differ from normal cells both in behavior and in chemical composition. Differences in the cell surface proteins exist between normal and malignant cells; since most, if not all, cell surface proteins are linked to sugar molecules, that is, are glycoproteins, it is of interest to look for abnormalities of such molecules among cancer patients. Glycoproteins may contain common simple sugars, more exotic sugars such as glucosamine, or complex sugar molecules such as sialic acid. To determine the possible relations between such molecules and cancer, researchers have measured total sialic acid, lipid-bound sialic acid, mucoid proteins, and protein-bound hexose sugars in the serum of patients and controls. The patients included 40 patients with oral cancer and 43 with precancerous lesions. The controls consisted of 47 healthy individuals and 18 tobacco-chewing subjects. For all proteins measured, the mean serum levels of the glycoproteins were greater among the cancer patients than among the healthy controls. Furthermore, the mean levels among the patients with precancerous lesions were greater than the healthy controls but were less than the patients with cancer. The sialic acid measurements and the measurement of mucoid proteins were on the average greater among the tobacco chewing subjects than among the healthy controls. When the cancer patients were considered separately, a correlation could be seen between the glycoprotein levels and the stage of the cancer. More advanced stages had higher levels of serum glycoproteins; this trend remained evident even when Stage III cancer patients were compared with Stage IV patients. The authors suggest that the measurement of glycoprotein levels might serve as a useful early detection test; in addition, the same measurements may aid in staging the extent of disease. (Consumer Summary produced by Reliance Medical Information, Inc.)

Diagnosis, Measurement, Glycoproteins, Mouth cancer, Sialic acids

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Utility and cost of carcinoembryonic antigen monitoring in colon cancer follow-up evaluation: a Markov analysis

Article Abstract:

Patients who have undergone surgery for colon cancer are at high risk for recurrence and are usually watched closely. Some studies have suggested an advantage can be obtained by monitoring carcinoembryonic antigen (CEA) in the blood. This antigen, present on some cancer cells, but not on normal tissues, may rise in the blood long before other symptoms of recurrence appear. However, the test is expensive, and false-positive results may be obtained. In addition, true-positive results may simply identify an impending recurrence for which no treatment is possible. Markov analysis was used to determine to what degree the use of the CEA screening actually improves the quality of life and life expectancy for colon cancer patients. The Markov analysis, which models sequences of events after assigning probabilities of jumping from one state to each of the possible succeeding states, was based upon risks and chances already published in the medical literature. The precise improvement in the patient's expectation of quality life depends on which data are chosen from published ranges. However, in all cases, any observed improvement was modest. While the improvement might be larger for some individuals, the average improvement in quality-adjusted life expectancy is likely to be less than one week. If the highest rate of return is achieved, the cost for CEA monitoring works out to $22,963 per year of quality life, while if the low-return figures for CEA monitoring are chosen, the same year costs $4,888,208. The statistical modelling of colon cancer survival presented suggests that the value of CEA monitoring has not been demonstrated sufficiently to justify routine use. (Consumer Summary produced by Reliance Medical Information, Inc.)

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