Vancouver, British Columbia-A study comparing continuousandrogen deprivation therapy (CAD) with intermittent androgendeprivation therapy (IAD) in prostate cancer post-prostatectomypatients with PSA found no statistically significant difference inprogression-free survival between the two treatment arms.
Ulf Tunn, MD, professor of urology and head of the department of urology, Akademische Stadtische Kliniken Offenbach in Frankfurt, Germany, presented the results of the multicenter phase III study at the International Study of Intermittent Therapy for Cancer of the Prostate meeting here.
According to Dr. Tunn, the results indicated that the estimated mean progression-free survival was 1,240 days in the intermittent androgen deprivation group and 1,010 days in the continuous androgen deprivation group. However, patients in the continuous treatment group developed significantly higher bone degradation than did the IAD patients, and quality of life was greater in the IAD group.
"Altogether, these parameters demonstrate that these were patients with unfavorable prognostic factors," he observed.
Men with PSA levels of >1.0 ng/mL after radical prostatectomy were recruited and treated for 6 months with leuprolide ace-tate in a European dose of 11.25 mg, which is 50% of the North American dosage, Dr. Tunn noted. After secondary PSA relapse to >.5 ng/mL, the men were randomized, with 96 in the IAD group and 78 in the CAD group. All received a flare-up prophylaxis of cyproterone acetate (not available in the U.S.) at the start of each androgen deprivation treatment.
Men in the intermittent androgen arm had their treatment paused after 6 months and restarted for 6 months when their PSA increased to >3.0 ng/mL. The endpoint was clinical or biological PSA progression while undergoing treatment.
Patients in the intermittent arm completed up to 35 cycles, with a mean duration of the off-treatment time of 62.5% in the first cycle. The duration of both the cycle and subsequent off-treatment time period were progressively shortened.
Ninety percent of these men achieved normal testosterone levels in the first cycle; however, "these findings proved to be less favorable from one cycle to the next," Dr. Tunn said.
Median time to progression was 1.86 years in the intermittent androgen group and 2.36 years in the continuous group. A log rank test of Kaplan-Meyer analysis indicated no significant difference between the two groups (p=.9852), although the estimated progression-free survival duration slightly favored the intermittent therapy group.
The patients have now been followed for 31 months. Final analysis will be completed within the next year, Dr. Tunn said.
Decreased cycle time
The numbers of patients in the intermittent androgen arm with completed treatment cycles decreased from 62% to 37%.