Goserelin. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic efficacy in prostate cancer.

Goserelin is a gonadotrophin-releasing hormone (GnRH) analogue which during long term administration reduces circulating levels of gonadotrophins (luteinising hormone and follicle stimulating hormone) and sex hormones. Goserelin is administered subcutaneously as a biodegradable depot formulation incorporating 3.6mg of the drug, which is released continuously over 4 weeks. In men with untreated advanced prostate cancer, monthly goserelin 3.6mg has been confirmed as similar in efficacy to surgical castration and diethylstilbestrol (stilboestrol) 3mg daily taken orally. Goserelin is better tolerated than diethylstilbestrol and appears to have a more favourable effect on quality of life than surgical castration. Treatment of prostate cancer with a combination of goserelin and an antiandrogen remains controversial as a result of inconsistent findings, despite extended data from a large trial which indicated an advantage for the combined regimen over surgical castration with respect to duration of time to progression and survival. Combination therapy also minimises the initial increase in signs and symptoms (disease flare) that occurs in up to 4% of patients at the beginning of treatment with a GnRH analogue. Surgical castration remains the treatment of choice in patients at risk of metastatic compression of the spinal cord or ureteric obstruction. However, goserelin is an effective alternative to surgery, or estrogen therapy, in men with previously untreated advanced prostate cancer. Goserelin seems to be preferred to surgery by the majority of patients given a choice of treatment, and importantly in a palliative care situation where there are no survival advantages for treatment alternatives, it appears to have a more beneficial effect on the quality of life than surgery.