Rapid Rise of Serum Testosterone Following Discontinuation of Long Term Treatment of Prostate Carcinoma with an LHRH-Agonist

Over the last six years, LHRH-agonists have been successfully used for the treatment of advanced prostate cancer. Testosterone levels identical to castrate levels have been reported after chronic treatment with LHRH-agonists. Long term effects on testicular histology following treatment with an LHRH-agonist and subsequent orchiectomy for disease progression revealed marked decrease in the number of Leydig cells and a partial or total arrest of sperm maturation [1,2]. Short term treatment with an LHRH-agonist indicated a return of plasma testosterone in patients with benign prostatic hyperplasia on discontinuation of the drug [3]. We report on long term treatment (l1⁄2 to 3 years) with an LHRH-agonist. Using the criteria of the National Prostate Cancer Project (NPCP), two of the three patients reported in table 1 had responded to the treatment with a partial response, whereas the third one was rated with stable disease. Four weeks following discontinuation of the last Zoladex injection, in two cases, A. H. and J. S., serum testosterone levels were still in the castrate range (below 50ng/l00ml), whereas a third patient exhibited a level already slightly above that cutoff level. Within the next 8 or 12 weeks, the testosterone levels had risen substantially in all three cases (table 1). It is likely that this recovery of serum testosterone is more rapid than the one reported by Tomic et al. [4] following long term treatment with an estrogen.