Evaluation of an amplified enzyme-linked immunoassay of placental alkaline phosphatase in testicular cancer.

The levels of serum placental alkaline phosphatase (PLAP) have been examined in 81 male controls, 51 untreated testicular tumours (41 seminomas and ten non-seminomatous testicular tumours) and 34 patients in complete remission (11 seminoma and 23 non-seminoma). Smoking induced a significant rise of serum PLAP in the controls, with a median level of 0.055 U/1 in non-smokers compared to 0.25 U/l in smokers. The levels found in pre-treatment seminoma (median 1.7 U/1) were significantly higher than in untreated teratoma (median 0.7 U/1). Treatment produced a significant fall in seminomas in remission (median 0.07 U/1). The role of PLAP in routine monitoring of seminomas was evaluated in 17 patients studied for 1-4 yr. PLAP shows similar trends to beta HCG but is an independent variable. The main role of PLAP is to help determine that the response to treatment has been satisfactory and that there are no unexpected foci of tumour.