Standardization and Practical Guidelines of Image DNA Cytometry in Clinical Oncology

DNA cytometry—both flow cytometry (FCM) and image cytometry (ICM)—has become an established technique in the field of analytical cellular pathology. These techniques are mainly used to obtain information about the nuclear DNA content of neoplastic parenchymal cells in human malignant tumors. The DNA ploidy pattern and the S-phase fraction offer tumor cell biological data that are supplementary to the often purely descriptive cytodiagnostic and histopathologic techniques. Diverging results among different laboratories have limited the value of DNA cytometry as a supplementary prognosticating tool, and this is the main reason why only a few clinical oncologic trials have the DNA data included in their protocols. The differences of the results seem to depend mainly on the methodological procedures used. In an effort to evaluate and to minimize sources of errors, particularly those originating from technical steps, the results of concomitant FCM and ICM DNA assessments on a large series of normal human cells and of cells of a broad spectrum of malignant tumors have been used to analyze each of the methodological steps in detail. Based on these observations, standardized procedures for sampling, fixation, staining and measurement were developed, as well as for data storage and evaluation of the ICM DNA histograms, together with guidelines for quality assurance.