Antiandrogen Withdrawal : Prostate
By prostate Doc at 16 September, 2008, 3:55 pm
Withdrawal of antiandrogens at progression is associated with a decline in PSA and improvement in clinical symptoms in approximately 20% of patients. The median duration of response is three to five months and is seen four weeks from with- drawal of flutamide.
The time to response is longer in patients receiving bicalutamide, probably because of its longer half-life. A multivariate analysis has shown that important predictors of response included initial treatment with CAB, baseline alka- line phosphatase level and duration of therapy. The mechanism of the antiandrogen withdrawal response is not fully under- stood; however, it appears to be at least partially related to mutation of the androgen receptor. The mutant receptors are paradoxically stimulated by antiandrogens. Rec- ognition of this response is important and should be tried before initiating other therapies.
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