The Dynamics of Serum Alpha‐fetoprotein in the Course of Testicular Teratoma

A retrospective study was carried out on a total of 279 cases of teratoma, out of which 135 were AFP positive, and 123 cases of seminoma. The AFP patterns were established by serial serum AFP assays carried out by radioimmunoassay at appropriately spaced time intervals. The following patterns could be distinguished: (1) Serum AFP levels normal throughout the whole course of the disease; (2) AFP levels consistently elevated irrespective of treatment; (3) normal levels for varying periods of time, then rising consistently; (4) elevated levels on presentation falling to normal for varying periods of time; (5) fluctuating with treatment, occasionally dropping to normal levels. Sequential AFP assays in patients with teratoma following orchidectomy, without evidence of residual tumour, suggest a half‐life of circulating AFP of approximately five days. A study was made to correlate any subsequent recurrence or absence of AFP elevation with the actual level of the patient's T½, compared with that of a normal T½ of five days. Appropriate formulas can be used to determine the patient's serum AFP T½ or to calculate the expected AFP level assuming a standard T½ of five days. The results suggest that a prolonged T½ is usually associated with recurrent elevations of serum AFP.