Antiandrogen withdrawal syndrome with nilutamide.

Antiandrogens are combined with medical or surgical castration to achieve total androgen blockade in metastatic prostate cancer. Discontinuation of antiandrogens at disease progression has been associated with prostate-specific antigen (PSA) decrease, symptom improvement, and occasionally objective tumor regression. Two cases of metastatic prostate cancer demonstrating decrease in PSA of 92% and 56% on discontinuation of nilutamide therapy are reported. Improvement in urinary symptoms, bone pain and, in one, disappearance of para-aortic lymphadenopathy paralleled the PSA decrease. The duration of the withdrawal response of 6 months was comparable to those reported with discontinuation of flutamide.