Serum tumour marker regression rate following chemotherapy for malignant teratoma.

The rate of fall of the serum tumour markers alphafetoprotein (AFP) and the beta sub-unit of human chorionic gonadotrophin (HCG) was analysed following platinum-based chemotherapy for metastatic non-seminomatous germ cell tumours. Of 90 evaluable patients 81% were alive and disease-free 1.5-4 yr (median 28 months) from the start of chemotherapy and 69 (77%) had remained continuously disease free. All three patients with an initial AFP half-life greater than 9 days relapsed; however, a further eight relapsing patients had an initial regression rate of serum AFP within the same range as patients remaining in remission (half-life 6-9 days). The HCG regression rate did not discriminate between patients remaining well or those who relapsed after chemotherapy. In 11 examples of a pattern of late slowing of the rate of marker fall (i.e. increasing half-life), five relapses were seen (45%), though this pattern was also observed in the context of large residual differentiated teratoma masses.