Patients with high-grade or metastatic prostate carcinoma are frequently medically or surgically castrated to inhibit the deleterious effects of testosterone. As a result, androgen deficiency can lead to a loss of libido and decreased sexual performance.102 Physicians have many options to induce androgen blockade, such as low-dose estrogens, luteinizing hormone-releasing hormone (LHRH) agonists, antiandrogens and orchiectomy.
The antiandrogens, like flutamide and bicalutamide, competitively inhibit the binding of testosterone and DHT to the androgen receptor.103,104 The goal of hormonal therapy is to provide maximal androgen blockade while minimizing sexual side effects. Several studies have evaluated the use of these agents and their affect on potency.
Migliari etal. showed that monotherapy with bicalutamide did not induce significant changes in nocturnal penile tumescence recordings or libido, sexual desire and frequency of sexual intercourse.103 This differs with studies on other antiandrogens, like medroxyprogesterone acetate and cypro-terone acetate, where the latter decreased sexual drive. This suggests that pure antiandrogen therapy does not impair sexual function.103,105 Schroder et al. reported that potency preservation with antiandrogen monotherapy using either flutamide or cyproterone acetate was not maintained.106 A loss of sexual function was found in roughly 80% of patients with either antiandrogen after 2 years of observation. They did note, however, that the loss of sexual function with both antiandrogens was gradual with 10-20% of men retaining sexual activity after 2-6 years of treatment.
LHRH agonists, like leuprolide and goserelin, decrease gonadotropin release, which suppresses testicular androgen production. LHRH agonists decrease sexual desire, sexual intercourse, and frequency, duration and rigidity of nocturnal erections when serum testosterone levels fall to castration levels.107 These agents are potent inhibitors of the male sexual response and must be used judiciously in younger patients who wish to preserve sexual function.
When bicalutamide was compared with flutamide plus goserelin in prostate cancer patients, fewer patients in the bicalutamide group had erectile dysfunction, which ensured a better quality of life.102 The bicalutamide group of patients enjoyed a higher emotional well-being, vitality and social functioning.
Finasteride and flutamide combined as androgen ablative therapy for advanced prostate adenocarcinoma have been studied. Finasteride inhibits 5a-reductase, decreases the conversion of testosterone to 5a-dihydrotestosterone and provides a more complete intraprostatic androgen block-ade.104 Combined therapy with these agents decreased serum prostate specific antigen (PSA) greater than either agent alone and accounted for an overall potency rate of 82% -with potency defined as the ability to maintain an erection satisfactory for sexual intercourse.104 Combined hormonal therapy has the promise of delivering sufficient androgen blockade while maintaining adequate erectile dysfunction. Greenstein et al. found that surgical castration with orchi-ectomy reduced serum testosterone to a level not statistically different than that with hormonal castration.108 Orchiectomy is associated with decreased potency and sexual activity.
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