Study of Combination Therapy for High Risk Prostate Cancer

This phase II trial studies the side effects and best dose of niraparib, and to see how well it works in combination with standard of care radiation therapy and hormonal therapy (androgen deprivation therapy) in treating patients with prostate cancer that has a high chance of coming back (high risk). Niraparib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Adding niraparib to the usual treatments of radiation therapy and hormonal therapy may lower the chance of prostate cancer growing or returning.

In order to participate you must meet the following criteria:

• Have histologically confirmed adenocarcinoma of the prostate at high risk for recurrence.
• Have no distant metastases on bone scan or lymph node assessment.
• Have no prior radical prostatectomy, cryosurgery for prostate cancer, or bilateral orchiectomy for any reason.
• Have no prior systemic therapy for prostate cancer (prior therapy for a different cancer is allowable).

This is a partial list of inclusion and exclusion criteria.