Measurement of nuclear DNA content in histological and cytological specimens: principles and applications.

Nuclear DNA content can be measured in histological and cytological material by the techniques of image and flow cytometry. The measurement depends on the availability of stoichiometric markers for DNA. Results are expressed in DNA histograms from which tumour DNA ploidy and cell proliferation status can be estimated. Flow cytometry analyses large numbers of cells and gives the most meaningful cell cycle data. Image cytometry is more specifically targeted to the population of interest and can accurately measure rare events. A large body of literature exists relating DNA cytometry to clinical outcome, but there are considerable inconsistencies between clinical series which may be due, in many instances, to problems of histogram interpretation and tumour sampling. Rapid 'user-friendly' systems currently under development may increase the clinical acceptance of DNA cytometry.