Plain language summary: Can declines in prostate-specific antigen level indicate how long patients with advanced prostate cancer will live when treated with enzalutamide?

WHAT IS THIS SUMMARY ABOUT?: This is a summary of a research article originally published in the . The PROSPER study involved men who had a type of advanced prostate cancer called non-metastatic castration-resistant prostate cancer (nmCRPC). In patients with nmCRPC, their prostate cancer keeps growing even after traditional hormone treatments. In these patients, rising prostate-specific antigen (PSA) levels suggest that cancer is active but CT and bone scans show that it has not spread to other parts of the body. Everyone in this study received androgen deprivation therapy (ADT) either with the medicine enzalutamide or a placebo. Enzalutamide is a medicine that can slow or stop androgens, such as testosterone, from making prostate cancer grow. The main results of the PROSPER study showed that patients with nmCRPC treated with enzalutamide and ADT lived longer than patients treated with placebo and ADT. In this study, researchers wanted to know if the findings were different depending on how much patients' PSA level declined after enzalutamide treatment. Researchers also wanted to know if this made a difference in how long patients lived without the cancer spreading to other parts of their body.

WHAT WERE THE RESULTS?: Researchers found that patients with a large decline in PSA level after treatment were more likely to live longer and without their cancer spreading.

WHAT DO THE RESULTS MEAN?: This study shows a link between PSA level changes and how long patients with nmCRPC live when treated with enzalutamide and ADT. These results may help health professionals monitor patients with different PSA level changes after enzalutamide treatment. Patients with a large decline in PSA level may not need to be monitored as closely as patients with a small decline in PSA level.