Lymphocyte urosynthase in non‐Hodgkin's lymphoma. An indicator of disease extensiveness

The activity of lymphocyte uroporphyrinogen synthase (URO‐S) was examined in 51 non‐Hodgkin's lymphoma (NHL) patients at various follow‐up periods. Mean ± SD activity (pmol prophyrin/mg protein/hr) at diagnosis (n = 24), on relapse (n = 14) and during active disease (n = 14) were 31.7 ± 19.8, 31.7 ± 27.2 and 29.4 ± 18.5, respectively. These values were significantly higher than the enzyme activity during remission (14.1 ± 4.0), which was in the normal range (14.5 ± 3.8). Abnormally high activity was found in 65.4% of determinations at diagnosis, on relapse and during active disease, compared to 5.5% during remission (P < 0.001). Significant association of abnormal URO‐S activity was found with advanced clinical stage (P < 0.01), spleen enlargement (P = 0.048), involvement of bone marrow (P = 0.02), as well as lymphoma cell spread to peripheral blood (P = 0.03). Highly significant correlation (r = 0.65, P < 0.001) was found between URO‐S activity and serum lactic dehydrogenase (LDH) levels. Excessively high levels of URO‐S activity were found only in patients with lymphoma cells in peripheral blood. No association was found with histopathologic classification and liver size. The authors conclude that URO‐S activity is a biochemical indicator for patients in all stages of NHL and seems to be a specific marker for the extensiveness of the disease. Cancer 59:89–93, 1987.