Intermittent vs Continuous Hormone Therapy in Prostate Cancer

Gerald Chodak, MD


March 15, 2011

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Hello. I'm Dr. Gerald Chodak from Medscape. At the 2011 ASCO [American Society of Clinical Oncology] conference, an interesting paper from Canada was presented looking at the effect of intermittent hormone therapy in men who had received radiation therapy and had a rising prostate-specific antigen (PSA).[1]

They compared intermittent hormone therapy with continuous hormone therapy, and each cycle of hormone therapy lasted for 8 months before being restarted when the PSA went again above 10 ng/mL. The study was designed to test for noninferiority, and that's why it was stopped. It had reached the endpoint that the intermittent therapy was noninferior to continuous hormone therapy.

There were some interesting differences. Men on intermittent therapy had fewer hot flashes, and they had a longer time to the development of hormone-refractory disease. There were no differences in fractures, osteoporosis, or heart attacks.

However, there was an important difference of which patients and doctors need to be aware. Although the overall survival rates were similar, there was a difference in death from prostate cancer. Men on intermittent hormone therapy were more likely to die of prostate cancer but less likely to die of other things. The death rate from prostate cancer in men on continuous therapy was 14%, but in the intermittent therapy group it was 17.3%, a 26% higher death rate from prostate cancer.

At the same time, the death from other causes was 60% in the men on continuous therapy vs 52.3% in the men on intermittent therapy. That difference amounted to a 14% higher death rate from other causes in the men getting continuous therapy. So if a patient is now presented with the option of going on hormone therapy when they have a rising PSA after radiation, a very careful message must be presented.

On the one hand, we can say that your overall survival seems to be similar whether you get continuous or intermittent treatment. At the same time, however, you are more likely to die of prostate cancer. Many men might find that to be an unappealing or unacceptable outcome. They would rather take the risk of dying of something else rather than from prostate cancer.

For these men, intermittent therapy may not be the right thing to do. At least we now have more information about counseling men who are considering intermittent treatment. For years we've been doing it without really knowing the impact on survival. Many people have hoped that overall survival might be better and -- at least based on this study -- that is not the case.

So in the end, men need to be carefully counseled about the overall outcome, the tradeoff of a lower incidence of adverse effects (such as hot flashes) and a delay in the development of hormone refractory disease but a greater likelihood of dying from prostate cancer. I look forward to your comments. Thank you.


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