Intermittent androgen suppression techniques yield similar results

May 1, 2011

Intermittent androgen suppression is as effective as continuous androgen deprivation, according to a non-inferiority study of men with a rising PSA following definitive primary therapy for prostate cancer.

Orlando, FL-Intermittent androgen suppression (IAS) is as effective as continuous androgen deprivation (CAD), according to a non-inferiority study of men with a rising PSA following definitive primary therapy for prostate cancer.

Regarding the economic implications of the findings, Dr. Klotz told attendees that patients treated with IAS were on therapy only 27% of the time, which reduces the cost of therapy on average by 73%.

The interim analysis was based on follow-up on 1,386 patients with rising PSA and non-metastatic prostate cancer after radical therapy (either radical prostatectomy or radiation therapy). Median follow-up was 6.9 years. Both treatment arms were well balanced for demographic and disease characteristics, including performance status, PSA level, prior radical prostatectomy, and time since radiation therapy.

Median overall survival was similar between the two arms: 8.8 years in the IAD arm versus 9.1 years in the CAD arm. Although time to development of castration resistance was close to 10 years and favored IAD, the study design was biased toward IAD, because in order to be re-treated, patients had to develop a rising PSA. More non-prostate cancer-related deaths were reported in the CAD arm (146 vs. 134 deaths, respectively), while more prostate cancer deaths occurred in the IAS arm (122 vs. 97 deaths, respectively).

Adverse events were similar between the two arms, with the exception of more hot flashes in the CAD arm.

Quality of life was improved in patients randomized to IAD when off therapy compared with CAD. Dr. Klotz said that quality of life data on treatment were still being analyzed and would be reported at a future date.

Results could be practice changing

Joel B. Nelson, MD, who was not involved with the study, predicted that the results would change practice.

"In this era of health care reform, we are pushed to reduce expenditures," said Dr. Nelson, professor and chairman of urology at the University of Pittsburgh Medical Center. "Androgen deprivation therapy constitutes a significant portion of the Medicare budget, and if these drugs are not necessary continuously, that will be cost-saving."