DNA content and prognosis of non-Hodgkin's lymphoma.

Ninety cases of non-Hodgkin's lymphoma diagnosed prior to the use of modern therapeutic regimens (1963-67) and 88 cases treated with such chemotherapy (1980-85) were studied using conventional morphology and flow cytometry. DNA aneuploidy as determined by flow cytometry was more common among high grade (38%) than low grade (19%) tumours (P less than 0.01). Measurements of proliferative index (S + G2 phase cells) revealed significantly increased values for high grade as compared with low grade lymphomas (P less than 0.001). In the first group of cases (1963-67) the relationship between histological grade and survival just failed to reach statistical significance over the long term (20 yr) (P = 0.1) but proved significant over 3 yr (P = 0.012). Differences in ploidy and proliferative index status were not associated with survival. In the second patient group (1980-85) attainment of complete remission following chemotherapy was associated with the presence of DNA aneuploidy in high grade tumours (P less than 0.05). The limited follow up of this group precluded assessment of survival in relation to ploidy.