Intermittent androgen deprivation: update of cycling characteristics in patients without clinically apparent metastatic prostate cancer

Abstract

Objectives. To update the cycling characteristics and patterns of treatment in patients receiving intermittent androgen deprivation (IAD) for clinically localized and recurrent prostate cancer. Methods. We report our experience with 61 patients treated with IAD. Thirty-four patients had received no prior treatment, and 27 had developed recurrent disease after previous local therapy. No patient had clinically apparent metastatic disease before the initiation of therapy. The mean and median serum prostate-specific antigen (PSA) level before treatment was 25.3 ng/mL and 16.0 ng/mL, respectively (range 0.5 to 190 ng/mL). For each cycle, androgen deprivation was continued until PSA became undetectable or a nadir level was reached. Patients were then observed without treatment, and therapy was reinstituted after the serum PSA value reached a predetermined level. Patients were no longer eligible to cycle off treatment when their serum PSA increased despite ongoing androgen deprivation or if any objective evidence of disease progression was present on imaging studies. Results. Follow-up ranged from 7 to 60 months (mean 30) from the start of treatment. Patients received from one to five treatment cycles (median two), with a median cycle length of 14 months. The median nadir serum PSA level during androgen deprivation was 0.01 ng/mL and was reached within an average of 6 months (range 4 to 9) after beginning treatment. Patients spent an average of 45% of the time not receiving therapy, but the time off therapy decreased as the number of treatment cycles increased. Five patients (8.1%) demonstrated progressive disease, with a median time to progression of 48 months. When examining the cycling characteristics of these patients, no consistent pattern of failure emerged. Conclusions. IAD appears to be a viable treatment option in select patients with localized prostate cancer. With each consecutive cycle, the amount of time the patient was not receiving therapy decreased, despite achieving a low nadir PSA. Longer follow-up with more patients failing IAD will be required before clear patterns of failure emerge in these patients.