Patient Summary: Phase III trial of intermittent MAB vs continuous MAB
This trial began with 766 patients with locally advanced or metastatic prostate cancer. These men were initially treated with three months of therapy consisting of 2 weeks of 200mg cyproterone acetate (CPA), and then monthly injections of an LHRH agonist with continued daily CPA. O f these patients, 626 had a fall in their PSA to either <4ng/ml or <80% of its initial value. These 626 men were then randomized to either intermittent or concurrent androgen deprivation (hormone therapy).
Patients had a PSA level checked every 3 months. For the intermittent group, androgen deprivation was restarted when their PSA rose to >10ng/ml with symptoms, >20ng/ml without symptoms, or by 20%, and was stopped when it dropped below 4 ng/ml.
50% of patients in the intermittent group have been off of therapy for at least 52 weeks following the initial therapy, and 29% of them have been off therapy for at least 36 months. When patients were required to restart therapy, they remained on therapy for a median of 14 weeks and then had a median of 70 weeks off therapy again. Patients with a PSA<2 at the time of randomization spent 82% of their time off therapy, whereas those with a PSA<4 were only off therapy for a median of 14 weeks. The intermittent group reported greater sexual activity, and this was the main difference affecting quality of life between the arms.
This study was conducted in Portugal, but in the U.S., most of the locally advanced stage patients would have been offered radiation therapy. The results here were not broken down by stage of disease. This study shows that patients with metastatic prostate cancer can receive effective treatment with intermittent hormone therapy.