Adaptive Radiation Therapy (ART) Stereotactic Ablative Body Radiotherapy (SABR) for Primary Localized Prostate Cancer

Inclusion Criteria: * Gender assigned male at birth: age ≥ 18 years * Histological confirmation of prostate adenocarcinoma * National Comprehensive Cancer Network (NCCN) (Prostate Cancer version 4.2022) low- to intermediate-risk prostate adenocarcinoma * Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2 * Ability to complete questionnaire(s) by themselves or with assistance * Signed informed consent * Willing to complete requirements for follow-up (during active monitoring phase) Exclusion Criteria: * NCCN (Prostate Cancer version 4.2022) very low-, high-, or very high-risk prostate adenocarcinoma * Prior definitive treatment of prostate cancer including radiotherapy, prostatectomy, cryotherapy, or high intensity focused ultrasound (HIFU) * Prior bladder outlet obstruction procedures including transurethral resection of the prostate (TURP), Holmium laser enucleation of the prostate (HoLEP), transurethral vaporesection of the prostate (TUVRP), etc. * Metastatic disease by conventional or molecular imaging * Contraindications to radiation therapy (RT) including uncontrolled inflammatory bowel disease, ATM mutation, and Xeroderma pigmentosum mutation * Concurrent antineoplastic agents (chemotherapy) * Previous or concurrent malignancy other than non-melanoma skin cancer, indolent lymphoma, or chronic myelogenous leukemia, unless continuously disease-free ≥ 5 years * Medical or psychiatric conditions that preclude informed decision-making or adherence with the protocol-defined treatment or follow-up * Prostate gland volume \> 80 cc based on magnetic resonance imaging (MRI), and/or International Prostate Symptom Score (IPSS) composite score \> 17 * Body weight \> 200 kilogram * Known allergy or sensitivity to polyethylene glycol (PEG) or iodine