Adrenal androgen blockade in relapsed prostate cancer

Abstract

The effectiveness of aminoglutethimide as an adrenal inhibitor has been well-documented by decreases in plasma testosterone and delta 4 levels, which fall significantly following the drug in previously orchiectomized patients. The use of cortisone or cortisol along with aminoglutethimide complicates the interpretation of the role of aminoglutethimide in effecting clinical responses. However, since physiologic replacement doses were used in most cases, a significant role for cortisone in effecting a clinical response is unlikely. Aminoglutethimide does have side-effects including rash and lethargy. It requires administration of replacement doses of cortisone and sometimes mineralocorticoid as well since it inhibits adrenal steroid synthesis in all pathways. Peripheral adrenal androgen inhibitors, such as flutamide, Megace, cyproterone acetate or 5 alpha-reductase inhibitors, in the future may be equally effective and simpler to administer than aminoglutethimide but objective and adequate numbers of studies using acceptable objective criteria must be done in order to adequately compare these drugs to aminoglutethimide. There appears to be approximately a 33% response rate (partial objective regression and objectively stable) following blockade of adrenal androgens in patients in relapse after castration. Blockade of adrenal androgen is certainly more tolerable and has many fewer side-effects than the alternative of chemotherapy which does not give response rates in most cases that are significantly different from those noted with aminoglutethimide. Murray's paper, combined with prior studies by Drago et al., goes a long way in establishing adrenal androgen blockade with that drug as the next step to be taken in patients following relapse from prior castration (medical or surgical). The most important question revolves around the timing of adrenal androgen blockade. As stated by Murray, will adrenal androgen blockade provide better survival if given earlier following relapse? The answer is not known yet. The answer may come from the work of Labrie [1], Geller and Albert [2] and others, who suggest that total survival in prostate cancer may be improved with blockade of adrenal androgens not after relapse following castration, but with panandrogen blockade at the time of initial therapy for prostate cancer.