The investigators present updated results with extended follow up evaluating whether intermittent therapy is associated with a shorter survival time. They studied 766 patients with locally advanced or metastatic prostate cancer who received a 3-month induction treatment with androgen deprivation therapy. 626 patients experienced a PSA decrease to below 4ng/ml or to 80% below the initial value and were then randomized. For therapy, patients received cyproterone acetate (CPA) 200 mg for two weeks and then monthly depot injections of a LHRH analogue plus 200 mg of CPA daily during induction. Patients randomized to the IAB arm ceased treatment while those randomized to the continuous arm received 200 mg of CPA daily and an LHRH analogue.
A total of 474 patients have died and 90 were lost to follow up. They found no difference in survival, p = 0.61, with hazard ratio 0.96 (95% CI 0.80 to 1.14). There were 239 deaths in the IAB arm and 235 in the continuous arm. A slight excess of cancer deaths in the IAB treatment arm (136 versus 109) is balanced by a slight excess of cardiovascular deaths in the continuous arm (68 versus 62), and deaths from other causes (58 versus 41). The hazard ratio of a cancer death is 1.27 (95% CI 0.98, 1.64), p = 0.06 in the IAB arm compared to the continuous. For cardiovascular deaths the hazard ratios are 1.05 (95% CI 0.75, 1.49), p =0.77, continuous compared to IAB and for other deaths the hazard ratio for continuous compared to IAB is 1.38 (95% CI 0.93, 2.06), p=0.11. The extended follow up has accumulated a further 135 deaths since the last analysis which used data up to 2005 and exceeds the number of events specified in the original power analysis. The extra 5 years of followup now means that the study has accumulated almost 3000 person years at risk among the 626 randomized patients and the median follow up is now 57 months compared to 51 months in the initial publication. They concluded that IAB should be considered for use in routine practice since it is associated with no reduction in survival, no clinically meaningful impairment in quality of life, better sexual activity, and considerable economic benefit.
Presented by Fernando M. Calais da Silva, et al. at the American Urological Association (AUA) Annual Meeting - May 14 - 19, 2011 - Walter E. Washington Convention Center, Washington, DC USA
Reported for UroToday by Christopher P. Evans, MD, FACS, Professor and Chairman, Department of Urology, University of California, Davis, School of Medicine.