Pn. Schlegel et al., Effective long-term androgen suppression in men with prostate cancer usinga hydrogel implant with the GnRH agonist histrelin, UROLOGY, 58(4), 2001, pp. 578-582
Objectives. To evaluate the effectiveness of a hydrogel implant containing
the gonadotropin-releasing hormone (GnRH) agonist histrelin in suppressing
testosterone production in men with prostate cancer and to determine the ef
fective dose (one, two, or four implants).
Methods. Forty-two men with prostate cancer and indications for androgen ab
lation were treated with one, two, or four implants. In two of the clinics,
comprising 27 subjects, the treatment period was 12 months, with replaceme
nt with the same number of implants at 12-month intervals. In a third clini
c, which treated 15 subjects, the implants were left in place for up to 30
months. The total experience was 605 treatment months.
Results. The histrelin levels were detected in serum proportional to the nu
mber of implants placed. The response, however, was similar among all three
dose levels, with testosterone and luteinizing hormone essentially complet
ely suppressed. Serum testosterone levels decreased from 21.9 +/- 17.6 nmol
/L to 0.93 +/- 1.57 nmol/L within I month and were maintained at 0.55 +/- 0
.24 nmol/L at 6 months and 0.60 +/- 0.28 nmol/L after 12 months of treatmen
t. Of the 38 assessable patients, 35 (92%) had castrate levels of testoster
one within 4 weeks of the initial implant placement. All patients followed
for up for 12 months after placement of the initial set of implants maintai
ned suppression of testosterone production while the implant was in place.
Conclusions. The histrelin hydrogel implant provided adequate and reliable
delivery of the potent GnRH agonist histrelin during at least I year using
a single implant in men with prostate cancer. No apparent advantages were f
ound in using more than one implant, and the question of the possible effec
tiveness of even lower doses remains open. This treatment modality appears
to be both safe and effective. (C) 2001, Elsevier Science Inc.