Hormone Therapy (Apalutamide) and Image-guided Stereotactic Body Radiation Therapy for the Treatment of Patients With Prostate Cancer, HEATWAVE Trial

Inclusion Criteria: * Confirmed diagnosis of prostate adenocarcinoma * Age ≥ 18 * Classified as having National Comprehensive Cancer Network unfavorable intermediate risk prostate cancer (i.e., \[a\] 2 of the following: PSA 10-20 ng/mL, clinical T category 2b-2c, or International Society of Urological Pathology \[ISUP\] grade group 2; \[b\] OR any 1 of \[a\] with ISUP grade group 3 disease; OR \[c\] any 1 of \[a\] with 50% or more cores on systematic biopsy showing prostate cancer) * Have a Decipher genomic classifier score * Have at least one dominant intraprostatic lesion visible on multiparametric MRI (Prostate Imaging-Reporting and Data System \[PI-RADS\] version 2.1 score 4 or 5) * Have underwent a prostate specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) * Have total testosterone \>= 150 ng/dL * Adequate performance status (Eastern Cooperative Oncology Group \[ECOG\] 0-1) * Hemoglobin ≥ 9.0 g/dL, independent of transfusion and/or growth factors within 3 months prior to randomization (at screening) * Platelet count ≥ 100,000 x 10\^9/uL independent of transfusion and/or growth factors within 3 months prior to randomization (at screening) * Serum albumin ≥ 3.0 g/dL (at screening) * Glomerular filtration rate (GFR) ≥ 45 mL/min (at screening) * Serum potassium ≥ 3.5 mmol/L (at screening) * Serum total bilirubin ≤ 1.5 x upper limit of normal (ULN) (Note: In subjects with Gilbert's syndrome, if total bilirubin is \> 1.5 x ULN, measure direct and indirect bilirubin and if direct bilirubin is ≤ 1.5 x ULN, subject may be eligible) (at screening) * Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) \< 2.5 x ULN (at screening) * Medications known to lower the seizure threshold (see list under prohibited medications) must be discontinued or substituted at least 4 weeks prior to study entry Exclusion Criteria: * Any evidence of spinal cord compression (radiological or clinical) * Prior pelvic malignancy * Prior pelvic radiation * Concurrent malignancy other than adequately treated basal cell or squamous cell skin cancer, non-muscle invasive bladder cancer (NMIBC), or any other cancer in situ currently without evidence of recurrence or progression * Inability to undergo radiotherapy, or hormonal therapy * Primary small cell carcinoma of the prostate (prostate adenocarcinoma with neuroendocrine differentiation is allowed) * Inflammatory bowel disease or active collagen vascular disease * History of any of the following: * Seizure or known condition that may pre-dispose to seizure (e.g. prior stroke within 1 year to randomization, brain arteriovenous malformation, Schwannoma, meningioma, or other benign central nervous system \[CNS\] or meningeal disease which may require treatment with surgery or radiation therapy) * Severe or unstable angina, myocardial infarction, symptomatic congestive heart failure, arterial or venous thromboembolic events (eg, pulmonary embolism, cerebrovascular accident including transient ischemic attacks), or clinically significant ventricular arrhythmias within 6 months prior to randomization * Current evidence of any of the following: * Uncontrolled hypertension * Gastrointestinal disorder affecting absorption * Known active infection (eg, human immunodeficiency virus \[HIV\] or viral hepatitis) * Any condition that in the opinion of the investigator would preclude participation in this study * Treatment with CYP2D6 substrates that have a narrow therapeutic index. If an alternative treatment cannot be used, a dose reduction of the CYP2D6 substrate may be considered * Baseline moderate and severe hepatic impairment (Child Pugh class B \& C)