Image: CC. Histology of prostate cancer.
1. Patients with metastatic castration-resistant prostate cancer survived longer on abiraterone plus prednisone vs. on prednisone alone.
2. Abiraterone plus prednisone increased the time to radiographic progression compared to patients taking prednisone alone.
Primer: Prostate cancer is the most common cancer in men and it is the second most common cause of death from cancer among men. Screening tests for this cancer have limitations, and several patients present with metastatic prostate cancer.
Standard medical treatment includes long acting GnRH analogs and anti-androgen receptor antagonists, which shut down the production of testosterone, an important signal for growth for prostate cancer. However, some cancers are able to produce their own testosterone and can no longer be treated in this fashion – these are termed castration-resistant.
Abiraterone is a drug that inhibits the enzyme cyp17, which is important in the production of testosterone. It has been shown to decrease symptoms as well as increase survival in patients with metastatic castration-resistant prostate cancer after chemotherapy with docetaxel.
Many providers eschew chemotherapy because of its limited benefits in this setting. Therefore, this study sought to determine whether metastatic castration-resistant prostate cancer patients would benefit from abiraterone plus prednisone without prior chemotherapy.
This [phase 3 double blind randomized controlled] study evaluated the use of abiraterone plus prednisone versus prednisone alone in men with metastatic castration-resistant prostate cancer who have not received chemotherapy and do not have cancer-related symptoms.
Patients who received abiraterone plus prednisone demonstrated delayed the progression of radiographic findings (soft tissue extension) by 8.2 months compared to those patients taking prednisone alone (16.5 vs 8.3 months, p<0.001). Furthermore, patients on abiraterone had longer latency periods for initiation of opiates, PSA progression, treatment with chemotherapy as well as decline in quality of life. Lastly, the data showed a positive trend toward increased survival. As a result, the trial was unblinded and patients in the prednisone alone group were moved to the abiraterone group.
In sum: Abiraterone plus prednisone appears to decrease progression while ameliorating symptoms and improving quality of life, and might also increase survival, in patients with metastatic castration-resistant prostate cancer.
This large study included patients from several countries. As very few therapies besides cytotoxic chemotherapy have been shown to increase patient survival, these promising results might prompt changes in the current management of metastatic prostate cancer.
By [JC] and [MP]
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