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On-and-off Approach to Prostate Cancer Treatment May Compromise Survival

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Key Points

  • In men with metastatic hormone-sensitive prostate cancer, there was a 10% relative increase in the risk of death with intermittent androgen deprivation therapy compared with continuous therapy.
  • Initial improvements in quality of life in the intermittent group were not sustained.

Taking a break from hormone-blocking prostate cancer treatments once the cancer seems to be stabilized is not equivalent to continuing therapy, a new large-scale international study finds.

Previous smaller studies had indicated that intermittent androgen deprivation therapy might be just as good as continuous androgen deprivation in terms of survival while meanwhile giving patients relief from the side effects of therapy. In fact, researchers believed intermittent therapy might help overcome treatment resistance that occurs in most patients with metastatic hormone-sensitive prostate cancer.

But this new study, which treated 1,535 patients with metastatic prostate cancer and followed them for a median of 10 years, finds that’s not the case. Results appear in the New England Journal of Medicine.

Study Details

“We tried to see whether intermittent androgen deprivation is as good as continuous androgen deprivation, but we did not prove that. We found that intermittent therapy is certainly not better and moreover we cannot even call it comparable,” said lead study author Maha Hussain, MD, FACP, a prostate cancer expert at the University of Michigan Comprehensive Cancer Center and Professor of Internal Medicine and Urology at the U-M Medical School.

The study was sponsored by the Southwest Oncology Group (SWOG), a National Cancer Institute-supported cancer clinical trials cooperative group.

In the study, men with metastatic hormone-sensitive prostate cancer were given an initial course of androgen deprivation therapy, which is standard therapy for this disease. Patients with a stable or declining prostate-specific antigen (PSA) level equal to or below a cutoff of 4 ng/mL were then randomly assigned either to continue or to discontinue the hormone therapy. Patients were carefully monitored with monthly PSAs and a doctor’s evaluation every 3 months, and therapy was resumed in the intermittent arm when PSA climbed to 20 ng/mL. The intermittent cycle continued on-and-off based on the PSA levels.

Survival among the two groups showed a 10% relative increase in the risk of death with intermittent therapy, with an average survival of 5.8 years for the continuous group and 5.1 years for the intermittent group from the time of randomization.

Quality of Life

Further, the researchers looked at quality of life between the two groups of patients. Initially, the intermittent therapy group showed significant improvement in impotence and emotional function in the first 3 months and improved trends in other aspects of quality of life compared to the continuous group. But these differences leveled off over time. 

“The improvements in some aspects of quality of life that were observed early were not sustained after a few months, as patients had to resume therapy,” said Dr. Hussain.

“If a patient is coming in with newly metastatic prostate cancer, hormone treatment continuously is the standard. If they wish to do intermittent treatment, they should be counseled that based on these data, their outcome might be compromised,” she added.

Follow-up studies are investigating a new generation of antihormone treatments combined with current therapies in the hopes of increasing the treatment’s effectiveness.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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