Objectives: To evaluate the use of intermittent androgen deprivation (IAD) in the treatment of selected patients with clinically localized prostate cancer.
Methods: We report our initial experience with 47 patients (aged 50 to 92 years) treated with IAD for clinically localized prostate cancer (Stage T1c in 3 patients, T2 in 21, T3 in 21, T4 in 1, and unknown in 1). No patient was found to have systemic disease prior to the initiation of therapy. Twenty-seven patients with localized cancers refused local therapy and have been treated with IAD only. Seven patients developed recurrent disease following radiotherapy, 2 following cryotherapy, 8 following radical prostatectomy, and 3 following radical prostatectomy with adjuvant radiotherapy. Mean and median serum prostate-specific antigen (PSA) prior to the start of treatment were 20.5 and 8.4 ng/mL, respectively (range 0.6 to 190). Androgen deprivation was continued 1 to 2 months after serum PSA became undetectable or a nadir level was reached. Therapy was then reinstituted after serum PSA reached a predetermined level. Thirty-three patients have been treated with total androgen blockade and 14 have been treated with a luteinizing hormone-releasing hormone agonist only.
Results: Follow-up ranges from 5 to 52 months from the start of treatment (mean 24 months). Patients have received from 1 to 5 treatment cycles (median 2 cycles), with the mean and median cycle lengths being 15 and 14 months, respectively. Eighteen patients are currently on cycle 1, 15 on cycle 2, 11 on cycle 3, 1 on cycle 5, and 1 patient has discontinued treatment after undergoing salvage radical prostatectomy. The mean and median nadir serum PSA on androgen deprivation have been 0.2 and 0.0 ng/mL, respectively. Nadir PSA was reached within an average of 4 months (range 1 to 11) after initiating treatment. The mean serum PSA at the start of cycle 2 was 7.0 ng/mL (range 0.6 to 19.1). Only 1 patient has failed to respond to reinstitution of treatment; this patient was found to have metastatic disease during his second cycle of treatment (time to progression 25 months from the start of IAD). No other patient has demonstrated disease progression during the follow-up period. Patients have spent an average of 47% of the time off of therapy.
Conclusions: IAD appears to be a viable treatment option in selected patients with clinically localized prostate cancer. However, the durability and advantage of IAD, if any, over continuous therapy is unknown at present. Consequently, at the present time IAD should be considered an investigative form of treatment for patients with prostate cancer.