Intermittent versus continuous hormone therapy in patients with metastatic prostate cancer

This research evaluated whether resistance to hormone therapy can be delayed by giving therapeutic injections with hormone therapy intermittently (start and stop) instead of continuously in patients with prostate cancer.

Androgens (testosterone) are male sex hormones which are made mainly in the testicles. They stimulate prostate cancer cells to grow. By lowering androgen levels or stopping them from getting to the prostate cancer cells often makes prostate cancers shrink, or to stop growing. This is called androgen deprivation therapy (ADT), and is a first line therapy for spreading prostate cancers, along with radiation therapy, surgery to remove the cancer or chemotherapy. ADT can include either surgical (removal of the testicles), or chemical castration using drugs (hormone therapy), which are given continuously.

However, most prostate cancer patients eventually develop resistance (they stop responding) to low androgen levels. Therefore the cancer continues growing despite ADT (a process called castration resistance). The efficacy of the treatment can be measured through the value of the blood prostate specific antigen or PSA (a protein produced by the prostate gland whose levels rise in prostate disease). If patients respond well to treatment, the PSA levels decrease and they increase again when the cancer stops responding to therapy. This study tested whether intermittent ADT delays castration resistance and has similar survival in prostate cancer patients compared to continuous ADT.  

This study included 1535 men with newly diagnosed metastatic (spread to distant organs or tissues) prostate cancer. All patients received standard ADT drugs for 7 months. After this initial therapy, patients were randomly assigned to receive continuous ADT (765 patients) or intermittent ADT (770 patients). This means that while the first group continued receiving hormone therapy, the second group stopped receiving the drugs. Patients were checked every 3 months. If a patient in the second group showed symptoms, or a rise in PSA blood levels (indicating worsening of the disease), standard treatment was resumed for another 7 months, and then stopped again.

Patients were followed up for approximately 10 years. Survival was an average of 5.8 years in the continuous therapy group versus an average of 5.1 years in the intermittent therapy group. However, patients in the intermittent therapy had better erectile function and mental health up to the third month of therapy, but not afterwards. Both treatment groups had similar amount of side effects due to treatment.

In summary, this research did not find intermittent ADT to be as efficient as standard continuous therapy regarding survival in patients with prostate cancer. It did, however, indicate a small improvement in quality of life in these patients.

The authors of the study found the findings of this study to be inconclusive. Future studies are needed to confirm these results.

Talk to your doctor about the most appropriate treatment option for your situation.