Variability in DNA measurements in multiple tumor samples of human colonic carcinoma

Article Abstract:

Flow cytometry provides a method for measuring the level of any substance within a cell for which a fluorescent marker is available. As such instruments have become more widespread, researchers have used them to measure the DNA content of cells from human cancers in the hope that this information may be of prognostic value. Indeed, many studies have demonstrated an association between abnormal DNA measurements and greater likelihood of adverse outcome. However, this is not true for all forms of cancer. As with any new technique, there may be technical problems with the method itself, which must be considered when interpreting results or devising ways to improve the technique's effectiveness. Researchers investigating the potential use of flow cytometry of DNA in the prognosis of colon cancer have identified a source of sampling error which may hamper the interpretation of results. Generally, flow cytometry is performed on small cancer specimens that can be spared by the pathology lab or on archival material. In the present study, investigators examined separately three samples each of 60 different colon cancers. In 38 cases, the DNA measurements on all three samples gave the same indication. In the remaining cases, one of the three samples yielded measurements different from the other two. In general, a DNA content that is indicative of an aneuploid chromosome complement, that is, having an abnormal number of chromosomes within the cell, is associated with an adverse outcome and is therefore the observation of interest. The results of the present study indicate that many tumors are diverse, and that the measurement of a normal diploid DNA content on any single sample may risk failing to identify aneuploid regions elsewhere in the tumor and misclassifying the chromosome complement as normal. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Colorectal cancer, Prognosis, Flow cytometry, Chromosome abnormalities, Chromosome numbers

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Prognostic significance of DNA cytometry in cutaneous malignant lymphomas

Article Abstract:

When infiltration of lymphoma cells into the skin occurs, a careful pathologic analysis is required. Conservative therapy may be adequate for low-grade lymphomas, while high-grade lymphomas may require aggressive treatment. The classification system for lymphoma grades is not entirely satisfactory; some cases that appear to be benign can have the same poor outcome as those involving malignant lymphoma. A study was undertaken to determine if DNA cytometry can be useful in evaluating cutaneous lymphomas. The principle behind cytometry involves the use of optical methods to measure the amount of DNA in individual cells. Often, tumors with abnormal amounts of DNA are more aggressive and result in a worse prognosis. Flow cytometry is often used in such measurements, but it is also possible to make these measurements using microscopic slides and a computerized image analysis system, which was done in the present study. An evaluation of 49 non-Hodgkin's lymphomas with either primary or predominant skin involvement was made, and an index reflecting the variation of nuclear DNA was developed. This index, called 2cDI, correlated strongly with the malignancy of the lymphoma. Patients with 2cDI less than 0.5 experienced no disease progression in the year following the analysis. In contrast, disease progression was observed in 57 percent of the patients with intermediate values, and in 64 percent of the patients with a 2cDI exceeding 1.0. The distribution of DNA within lymphoma cells may prove to be a valuable indicator of malignancy in cutaneous lymphoma. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, Genetic aspects, Non-Hodgkin's lymphomas, Ploidy, Aneuploidy, Diploidy

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