tailieunhanh - Chapter 091. Benign and Malignant Diseases of the Prostate (Part 9)

Antiandrogens Nonsteroidal antiandrogens such as flutamide, bicalutamide, and nilutamide block the binding of androgens to the receptor. When an antiandrogen is given alone, testosterone levels remain the same or increase. Compared to testosteronelowering therapies, antiandrogens cause fewer hot flashes, less of an effect on libido, less muscle wasting, fewer personality changes, and less bone loss. Gynecomastia remains a significant problem but can be alleviated in part by tamoxifen. Antiandrogens were approved initially to block the flare that results from GnRH analogue administration. They have also been studied as monotherapy and as part of a combined androgen blockade (also called maximal androgen blockade) | Chapter 091. Benign and Malignant Diseases of the Prostate Part 9 Antiandrogens Nonsteroidal antiandrogens such as flutamide bicalutamide and nilutamide block the binding of androgens to the receptor. When an antiandrogen is given alone testosterone levels remain the same or increase. Compared to testosteronelowering therapies antiandrogens cause fewer hot flashes less of an effect on libido less muscle wasting fewer personality changes and less bone loss. Gynecomastia remains a significant problem but can be alleviated in part by tamoxifen. Antiandrogens were approved initially to block the flare that results from GnRH analogue administration. They have also been studied as monotherapy and as part of a combined androgen blockade also called maximal androgen blockade . Most reported randomized trials suggest that the cancer-specific outcomes are inferior when antiandrogens are used alone. Bicalutamide even at 150 mg three times the recommended dose was associated with a shorter time to progression and inferior survival compared to surgical castration for patients with established metastatic disease. Nevertheless some men may accept the trade-off of a potentially inferior cancer outcome for an improved quality of life. Combined androgen blockade the administration of an antiandrogen plus a GnRH analogue or surgical orchiectomy was designed to inhibit both testicular and adrenal androgens at the outset. Cumulative results of randomized comparisons involving thousands of patients showed no advantage for combining an antiandrogen with surgical orchiectomy while separate analyses of trials combining an antiandrogen with a GnRH analogue have shown a modest 10 survival advantage. Meta-analysis of all combined androgen blockade trials concluded that the approach was not more effective. In practice most patients treated with a GnRH analogue receive an antiandrogen for the first 2-4 weeks of treatment to protect against the flare. Intermittent Hormone Therapy Another way to