The significance of new abnormal isoenzymes of 5'-nucleotide phosphodiesterase in the diagnosis of human liver cancer.

In 1986, we reported that abnormal 5'-nucleotide phosphodiesterase (5'-NP) (oligonucleate: 5'-nucleotidohydrolase, EC 3.1.4.1) isoenzymes (5'-NP I and 5'-NP V + VI) were observed in the serum of patients with liver cancer. The results of the present study show that the 5'-NP I positivity rate is 99.2% (234/236), specificity 74.9%; and the 5'-NP V + VI positivity rate is 77.5% (183/236), specificity 95.3% in liver cancer. 5'-NP I positivity rate is 86.7% (13/15) and 5'-NP V + VI positivity rate is 46.7% (7/15) in metastatic liver cancer. These 3 abnormal isoenzyme bands were all present in the serum of 6 patients with liver cancer before radical resection and disappeared after successful resection, but they were all present in the serum of 6 other liver cancer patients before and after palliative operation. In 2 cases of small liver cancer (diameter less than 4cm), 5'-NP I and 5'-NP V + VI were strongly positive. It may be considered that the new 5'-NP abnormal isoenzyme bands are specific markers and will be useful for diagnosis of human liver cancer.