• Tumour marker;
  • placental alkaline phosphatase;
  • seminoma

Objective To investigate the significance of placental alkaline phosphatase (PLAP) as a tumour marker for seminoma.

Patients and methods A total of 673 serum samples from 116 patients with testicular germ cell tumours (78 seminomas and 38 non-seminomas) were analysed for several markers including PLAP, total alkaline phosphatase (AL-P), alpha fetoprotein (AFP), beta human chorionic gonadotrophin (HCG-B), and lactic dehydrogenase (LDH).

Results Serum PLAP was increased initially in about 50% of patients with seminoma, and the mean magnitude of elevation was about five times the normal value. There was no significant correlation between PLAP and LDH or between PLAP and HCG-B. Therefore, a combination of these three markers was of value, and resulted in a positive identification rate of 82% of patients with seminoma. False-positive results for PLAP appeared in 1.6% of 673 samples investigated.

Conclusion The monitoring of serum PLAP might be of value, as fluctuations in this marker provide information about disease status and prognosis.