Plasma testosterone and androstenedione after orchiectomy in prostatic adenocarcinoma

SUMMARY Orchiectomy is often used in the management of metastatic adenocarcinoma of the prostate, an androgen dependent tumour, since it markedly reduces the concentrations of plasma testosterone (to a mean level of 28 ± 16 (SD) ng/100 ml) and temporarily inhibits the growth of the neoplasma. In some orchiectomized patients, however, the values of plasma testosterone and androstenedione do not drop to these levels, but remain higher, around 137 ± 23 ng/100 ml and 213 ± 39 ng/100 ml respectively. In these patients, treatment with dexamethasone significantly decreased the levels of testosterone and androstenedione to 22 ± 20 ng/100 ml ( P <0.0005) and 43 ± 11 ng/100 ml ( P <0.0005) respectively. It can therefore be assumed that in orchiectomized patients these compounds are produced in the adrenal cortex, which in some cases is stimulated to produce a larger amount of strong androgens such as testosterone and weaker androgens such as androstenedione. It has also been observed that those patients with an inadequate lowering of plasma testosterone levels after orchiectomy, did not show clinical improvement. Further studies in a larger number of patients are needed in order to support this finding.