Intermittent and continuous androgen deprivation therapies offer patients with relapsing or locally advanced prostate cancer (PCa) similar efficacy, tolerability and quality-of-life profiles, a new study suggests.

In an open-label phase 3b trial, Claude Schulman, MD, of Clinic E Cavell and the University of Brussels in Belgium, and colleagues randomly assigned 701 patients to receive either continuous androgen deprivation (CAD) or intermittent androgen deprivation (IAD) following a 6-month induction with leuprorelin acetate 22.5 mg 3-month depot. All patients had non-metastatic locally advanced PCa or elevated or rising PSA levels following radical prostatectomy or radiotherapy.

At 36 months, the CAD and IAD groups did not differ significantly with respect to time to PSA progression, the trial’s primary outcome, Dr. Schulman’s team reported online ahead of print in European Urology. The median time to PSA progression was not reached. The estimated 3-year PSA progression rate was 10.6% and 10.1% for the CAD and IAD groups, respectively. The estimated PSA progression-free survival rates for the CAD and IAD groups (13.2% and 13.1%, respectively) also did not differ significantly.

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The estimated 5-year overall survival (OS) rates for the CAD and IAD groups were 85% and 81.8%, respectively, a non-significant difference.

In addition, quality of life (QoL) as measured using the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 was comparable for both groups. For the functional scales, the mean scores were all above 80, with no notable changes during the randomized phase, according to the investigators. The treatment arms also showed no significant differences in the proportion of patients suffering treatment-emergent adverse events (TEAEs) and treatment-related TEAEs. The groups also had similar rates of hot flushes, hypertension, constipation, back pain, and fatigue.

“The principal potential benefits of IAD compared with CAD included reduced drug acquisition costs with comparable OS rates,” the researchers concluded. “There were no apparent differences in QoL benefits between the treatment groups.”

The median number of IAD injections given during the randomized phase was 3 (range 1–10) compared with 12 (range 1–12) for the CAD group, with a mean duration of 327 days and 89 days between injections for the IAD and CAD groups, respectively.

A total of 131 men (19.1%) withdrew from the trial after randomization—70 in the CAD group and 61 in the IAD group.