Clinical Experience with Intermittent Androgen Suppression in Prostate Cancer: Minimum of 3 Years' Follow-Up.

This report reviews the long-term follow-up of a prospective Phase II evaluation of intermittent androgen suppression in the treatment of prostate cancer. A total of 87 patients have been entered in this protocol. At the time of this report, 50 men have been followed for a minimum of 3 years. Treatment was initiated with combined androgen blockade and continued for at least 6 months until a serum PSA nadir was observed. Medication was then withheld until the serum PSA increased to mean values between 10 and 20 ng/mL. This cycle of treatment and no treatment was repeated until the regulation of PSA became androgen independent. The total time in the study ranges from 40 to 126 months, with a mean of 65.5 months. The off-treatment period in the first cycle for the men with long-term follow-up was associated with an improvement in the sense of well-being and recovery of libido and potency in men who reported normal or near-normal sexual function before the start of therapy. The average time off therapy (percentage time off therapy) for cycles 1, 2, 3, and 4 was 15 months (54%), 10 months (48%), 8 months (45%), and 7 months (40%), respectively. The study group included 9 patients treated because of a rising PSA concentration after radiation therapy for locally advanced cancer. These patients have been off therapy for an average of 22 and 13 months in treatment cycles 1 and 2, respectively. Six patients with rising PSA values after radical prostatectomy and with follow-up exceeding 36 months have been off therapy for an average of 19 and 11 months in treatment cycles 1 and 2, respectively. Of the 87 patients, 23 have had their disease progress to androgen independence at a median of 32 months of treatment, and 13 have died cancer-specific deaths at a median of 48 months. Prostate cancer is amenable to control by intermittent androgen suppression. This approach affords an improved quality of life when the patient is off therapy, with reduced toxicity and costs. Phase II trials suggest that there is not a negative impact on patient outcome. Randomized protocols are currently in progress to determine whether survival is affected in a beneficial or adverse way by such treatment in men with locally recurrent or metastatic cancer.