Intermittent versus Continuous Hormone Therapy for PCa

Dr. Klotz from Toronto presented the mature data from a very large multi-center (we participated) trial comparing the use of intermittent androgen suppression (8 months “on” and wait until PSA reaches 10 before restarting) with continuous suppression. These were all patients who had PSA recurrence after radiotherapy to the prostate and rising PSA >3 who were at least 1 year after completing therapy. Among the 1386 patients randomized there was no difference in survival (9.1 vs 8.8 years) between the two approaches. Slightly more prostate cancer deaths occurred in the intermittent arm but this was balanced by slightly more non-prostate cancer deaths in the continuous arm. The quality of life analysis has not been reported, but numerous similar (smaller) studies show that intermittent treatment is better tolerated. I agree with Dr K that intermittent therapy should be the standard of care for patients who need hormone treatment. It remains unclear what the optimal “on” and “off” intervals might be (or how high to let the PSA rise before resuming treatment). Many of my patients are nervous about letting their PSA go up, but this report is reassuring. A similarly large trial in patients with rising PSA after surgery will probably be reported in the next few years. I expect it will show the same thing.