Preliminary observations on the application of carcino-placental alkaline phosphatase to the investigation of patients with seminoma of the testes.

Suitable tumour markers for monitoring the treatment of seminoma of the testis have not yet been established in clinical practice. Carcino-placental alkaline phosphatase (CPAP) has been suggested for this purpose but it is difficult to detect and specifically analyse this enzyme. We have devised an immunoenzymatic method of analysis in which cross-reactions with liver type and intestinal alkaline phosphatase are minimal and we have applied this test to seven patients with histologically proven seminoma. CPAP was raised in 4 patients prior to treatment and chorionic gonadotrophin in two of these. Alpha-fetoprotein was normal in all cases. We conclude that the use of CPAP in monitoring treatment of testicular seminoma is worthy of further attention.