What is this summary about?This is a plain language summary of two research articles originally published in the New England Journal of Medicine and NEJM Evidence.The EMBARK study included patients with a type of advanced prostate cancer called non-metastatic castration-sensitive prostate cancer (nmCSPC) and high-risk biochemical recurrence (BCR).These patients experience a quick rise in prostate-specific antigen (PSA) levels after prostate cancer surgery or radiation treatment. Patients with a shorter PSA doubling time (PSADT) have quickly rising PSA levels. The patients from EMBARK had a short PSADT of 9 months or less, and their prostate cancer had not spread to other parts of the body. Prostate cancer treatments that lower testosterone levels, such as leuprolide, are widely used in patients with nmCSPC and high-risk BCR.In the EMBARK study, researchers wanted to know if enzalutamide treatment with or without leuprolide improved outcomes compared with leuprolide and placebo in patients with nmCSPC and high-risk BCR. Researchers also looked at the safety of these medicines and their effect on quality of life.What were the results?Researchers found that patients who received enzalutamide with or without leuprolide had a longer time until cancer spread to other parts of the body or death. It also took longer for their PSA levels to rise further and for them to start a new prostate cancer treatment.No new side effects were seen in the enzalutamide groups beyond those already known for enzalutamide. The most common side effects in all groups were hot flash, tiredness, and joint pain. The common side effects in the enzalutamide alone group were gynecomastia and breast tenderness.The median time that it took until patients had a confirmed drop in overall quality of life was similar between the enzalutamide combination, the enzalutamide alone, and the leuprolide plus placebo groups.What do the results of the study mean?Enzalutamide with or without leuprolide improved outcomes in patients with nmCSPC and high-risk BCR without making overall quality of life worse. The amount and type of side effects in the enzalutamide groups were similar to the findings from past studies. These results may help doctors and patients choose the right treatment for nmCSPC and high-risk BCR.Who should read this article?This summary is for anyone interested in knowing more about this topic, regardless of background, knowledge, or education.[Box: see text].