ATLANTA -- Attacking locally advanced prostate cancer with intermittent androgen treatment may improve quality of life while maintaining the historical survival of more aggressive therapy.
ATLANTA, Sept. 17 -- Attacking locally advanced prostate cancer with intermittent androgen treatment may improve quality of life while maintaining the historical survival of more aggressive therapy.
So reported Nicholas Bruchovsky, M.D., Ph.D., of Vancouver General Hospital and the University of British Columbia. He maintains that the intermittent regimen appears to delay progression from treatable androgen-dependent cancer to untreatable androgen-independent disease.
"We like to say that we are hitting the cancer with a flyswatter rather than using a sledgehammer," he said at the Department of Defense Prostate Cancer Research conference here.
In his single-arm treatment trial that included 103 eligible men, the observed survival after six years is about 80%, he said. The expected survival is about 70%, he added.
Dr. Bruchovsky recruited men who had undergone external beam radiation for treatment of prostate cancer, but whose rising PSA indicated a recurrence of the disease. The men were treated with androgen suppression until the PSA normalized at about 4 mcg/L. He then followed the men and when PSA again rose about 10 mcg/L, the patients underwent further treatment with cyproterone acetate or leuprolide acetate until the PSA dropped again.
"Biochemical recurrence after irradiation of localized prostate cancer proved amenable to cyclic androgen suppression with a high response rate," Dr. Bruchovsky said. "About 95% of the patients in the study did respond." The average age of the men in the study at the time of enrollment was about 73 years.
"I have treated men with this regimen who remain alive and will functioning 15 to 20 years later," he said.
The time between treatments -- after suppressing PSA below 4 mcg/L -- lasted as long as 75 weeks following the first treatment. The time off-treatment before PSA rebound generally was shorter. For example, after the second treatment period, the off-treatment interval was about 60 weeks. After the third treatment, the off-treatment interval was about 39 weeks.
Dr. Bruchovsky noted that the lower the PSA went down, the shorter the interval between treatments. "Nadir PSA was a powerful predictor of early progression to androgen independence," he said.
During the study, the researchers also measured multiple factors involving quality of life and particularly sexual quality of life. "Quality of life scales improved in the off-treatment interval," Dr. Bruchovsky said.