Intermittent Androgen Deprivation for Patients with Recurrent/Metastatic Prostate Cancer

This study was designed to assess the duration of response to intermittent androgen deprivation therapy (IAD) in patients with recurrent and/or metastatic prostate cancer. Between January 1993 and March 2000, 74 patients with recurrent and/or metastatic prostate cancer had IAD with either luteinizing hormone-releasing hormone agonist (LHRH) or an LHRH with an oral antiandrogen. Forty-one patients were treated for an increasing prostate-specific antigen (PSA) level after primary local treatment. Of the remaining 33 patients, 17 patients were treated for metastases (9 for bone metastases, 8 for lymph nodes metastases, and 16 for local recurrence). Patients who had undergone IAD completed between 1 and 6 cycles. A cycle was defined as the period during which the patient was actively taking the hormone medication. Seventy-four patients completed the first cycle, 49 completed the second cycle, and 23 completed the third cycle. The pattern of PSA changes with each cycle, the length of each cycle, and the time interval between successive cycles were studied. The time to progression (defined as an increasing PSA level on two consecutive measurements or radiologic evidence of progression of disease while the patient was on androgen deprivation) was also studied. The median PSA before the IAD was 11.4 ng/mL (range 0.12-378). The median PSA nadir at the end of each cycle increased progressively (0.1 ng/mL after the first cycle to 3.3 ng/mL after the fifth cycle). The time interval between the cycles progressively decreased from 9.5 months between the first and second cycles to 6 months between the third and fourth cycles. The 4-year actuarial androgen-independent free survival was 71%. For the subgroups of patients treated for biochemical failure, locoregional recurrence, and bone metastases, the 4-year actuarial progression-free survival rates were 80%, 67%, and 45% respectively (P = 0.018). The median time of 18 months to progression in patients with bone metastases is similar to that reported with continuous hormonal therapy. In patients with biochemical failure, the median time to progression (more than 5 years) suggests that the IAD approach may be a viable option for this group of patients.