Oestrogen pre-treatment abolishes luteinising hormone-releasing hormone testosterone stimulation.

In patients with histologically confirmed prostate cancer, oestrogen priming with diethylstilboestrol (DES) (3 mg/day) for 4 weeks prior to the first injection of the LHRH agonist Zoladex (3.6 mg depot form) prevented any rise in the serum testosterone concentration. In contrast, in the groups pre-treated with DES, the first, but not subsequent, injections with Zoladex were associated with a marked surge in luteinising hormone. Treatment with DES beyond the time of the first administration of Zoladex did not provide further endocrinological advantage. Oestrogen priming for 1 month prior to treatment with Zoladex may prevent an exacerbation of signs and symptoms of prostate cancer.