An Efficacy and Safety Study of JNJ-56021927 (Apalutamide) in High-risk Prostate Cancer Subjects Receiving Primary Radiation Therapy: ATLAS

Inclusion Criteria: * Age \>= 18 years * Indicated and planned to receive primary radiation therapy for prostate cancer * Histologically confirmed adenocarcinoma of an intact prostate, and 1 of the following at diagnosis: 1) Gleason score \>=8 and \>=cT2c, 2) Gleason score 7, PSA \>=20 nanogram per milliliters (ng/mL), and \>=cT2c * Charlson index (CCI) \<=3 * An Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) grade of 0 or 1 * Adequate organ function: (1) aspartate aminotransferase (AST), alanine aminotransferase (ALT), within normal limits (WNL), (2) serum creatinine less than (\<) 1.5 milligram/deciliter (mg/dL) (\<133 micromoles/Liter \[mcmol/L\]), (3) platelets greater than or equal to (\>=)140,000/microLiter (mcL), independent of transfusion and/or growth factors within 3 months prior to randomization, (4) Hemoglobin \>= 12.0 gram/deciliter (g/dL) (7.4 millimloes \[mmol\], independent of transfusion and/or growth factors within 3 months prior to randomization * Participants who are sexually active (even men with vasectomies) and willing to use a condom and agree not to donate sperm during the trial * Signed, written, informed consent * Be able to swallow whole study drug tablets Exclusion Criteria: - * Presence of distant metastasis, (clinical stage M1). Isolated pelvic nodal disease below the iliac bifurcation (clinical stage N1) is not an exclusion. Diagnosis of distant metastasis (clinical M stage; M0 versus M1a, M1b, M1c) and pelvic nodal disease (clinical N stage; N1 versus N0) will be assessed by central radiological review. Patients are considered eligible only if the central radiological review confirms clinical stage M0 * Prior treatment with gonadotropin releasing hormone (GnRH) analogue or anti-androgen or both for \>3 months prior to randomization * Bilateral orchiectomy * History of pelvic radiation * Prior systemic (example \[e.g.\], chemotherapy) or local (e.g. radical prostatectomy, cryotherapy) treatment for prostate cancer * History of seizure or any condition that may predispose to seizure (including, but not limited to prior stroke, transient ischemic attack or loss of consciousness \<= 1 year prior to randomization; brain arteriovenous malformation; or intracranial masses such as schwannomas and meningiomas that are causing edema or mass effect) * Prior treatment with enzalutamide, abiraterone acetate, orteronel, galeterone, ketoconazole, aminoglutethimide, estrogens, megestrol acetate, and progestational agents (including cyproterone acetate) for prostate cancer * Prior treatment with radiopharmaceutical agents (e.g., strontium-89) or immunotherapy (e.g., sipuleucel-T) for prostate cancer * Prior treatment with systemic glucocorticoids ≤4 weeks prior to randomization or is expected to require long-term use of corticosteroids during the study * Use of 5-alpha reductase inhibitors (e.g., dutasteride, finasteride) \<=4 weeks prior to randomization * Use of any investigational agent \<=4 weeks prior to randomization * Current chronic use of opioid analgesics for \>=3 weeks for oral or \>= 7 days for non-oral formulations * Major surgery \<=4 weeks prior to randomization * Current or prior treatment with anti-epileptic medications for the treatment of seizures * Gastrointestinal conditions affecting absorption * Known or suspected contraindications or hypersensitivity to apalutamide, bicalutamide or GnRH agonists or any of the components of the formulations * Any condition for which, in the opinion of the investigator, participation would not be in the best interest of the subject