Intermittent hormone therapy in nonmetastatic prostate cancer

The object of this study was to evaluate the duration of response to intermittent androgen deprivation (IAD) in patients with nonmetastatic recurrent or localized prostate cancer.

One hundred ten patients received IAD from February 1992 to February 2005. One hundred three patients were treated after failure of primary radiation therapy and/or prostatectomy, with the remaining 7 patients treated primarily with IAD. The median duration of treatment cycle was 6 months. Patients were considered resistant to hormone therapy if the prostate-specific antigen (PSA) level increased, with castrate levels of testosterone. At the time of initial diagnosis, the median Gleason score was 7 (range, 4-9), and tumor stages were as follows: T1/T2 (n = 73), T3 and T4 N1 (n = 34), and other (n = 3). The median PSA at the initiation of IAD was 8.25 ng/mL.

The median follow-up after beginning IAD was 45.5 months. Patients received a median of 2 cycles (range, 1-9 cycles). Ninety-four of 110 patients (85.5%) remained responsive to IAD. Sixteen patients (14.5%) progressed to become refractory to primary hormone treatment. Patients with a higher tumor stage (T3 and T4) were significantly more likely to develop resistance. The median time to become refractory to hormone therapy was 47.9 months (range, 9.4-93.4 months). Five patients were put on secondary continuous hormone treatment, and 3 of them developed resistance at a median of 9 months. One patient was put on a secondary IAD and was still responding at the last follow-up.

With 85.5% of the original patient population still responding to the primary hormone therapy at 45.5 months of follow-up, IAD appears to be a viable option for patients with biochemical failure after local radiation therapy. A pattern of shortening time between cycles and an increasing nadir PSA level with each successive cycle is consistent with the gradual development of hormone resistance.