Frequency of serum tumour marker monitoring in patients with non-seminomatous germ cell tumours.

In patients relapsing on surveillance following orchidectomy for stage 1 non-seminomatous germ cell tumours, it is essential that treatment is initiated before they develop advanced disease with a poor prognosis. Patients who start chemotherapy with levels of human chorionic gonadotrophin (HCG) greater than 1,000 i.u. l-1 and/or alpha-fetoprotein (AFP) level greater than 500 ku l-1 have been shown to have a worse prognosis than patients with lower marker levels. We studied 64 patients between 1968 and 1987 with rising serial tumour markers. The potential time in which markers could rise to poor prognostic levels was calculated assuming an exponential rate of increase. Adverse levels were predicted in one patient (1.6%) within 7 days, in two patients (3.1%) within 14 days, in eight patients (12.5%) within 4 weeks and in 16 patients (25%) within 6 weeks. This suggests that, initially, weekly marker estimations should be performed on stage 1 surveillance patients. The extra cost to a specialist follow-up laboratory of weekly as opposed to the usual monthly marker measurements will be less than 33,600 pounds for every 400 patients on surveillance. One extra patient is likely to be cured for this sum.