THE PROGNOSTIC-SIGNIFICANCE OF THE DNA CONTENT IN EWINGS-SARCOMA - A RETROSPECTIVE CYTOPHOTOMETRIC AND FLOW CYTOMETRIC STUDY

The DNA content of the cell nuclei of Ewing's sarcoma was analysed by means of cytophotometry in situ with image analysis in Feulgen-stained sections in 37 patients, and by retrospective flow cytometry accordin g to the method of Hedley in 26 patients. Different histogram patterns were obtained: normal unimodal or bimodal DNA distributions and abnor mal DNA distributions with one or two stem lines, or an abnormal DNA d istribution with no stem lines. Both methods enabled us to make a dist inction between two groups of Ewing's sarcomas with a different progno sis. All patients with aneuploid tumours died within 5 years after the initial diagnosis. Eleven of 19 (58%) patients with a normal DNA dist ribution in their tumour, as determined by cytophotometry, are still a live and in good health with a mean survival period of 7.5 years, rang ing from 2 to 19 years. Of the group of patients in which flow cytomet ry revealed a normal DNA pattern. eight of 15 (53%) are still alive an d in good health, with a mean survival period of 8 years. These result s indicate that both techniques are reliable methods for obtaining pro gnostic information in Ewing's sarcomas. However, cytophotometry in si tu yielded a better discrimination for the overall survival (P < 0.01) than did flow cytometry (P<0.05). In 19% of the cases there was a dis crepancy between the DNA histograms obtained with the two techniques. In five of 26 cases the DNA distributions were classified as normal by one method and aneuploid by the other. Tumour cell representation or selective loss of cells during enzymatic treatment may be responsible for this discrepancy.