Stereotactic Body Radiotherapy vs Intensity-modulated Radiotherapy in Prostate Cancer

Inclusion Criteria: * Histological confirmation of prostate adenocarcinoma * Low or intermediate risk prostate cancer patients (i.e. T1-T2c and PSA 20 and Gleason score \< 8) with the risk of pelvic node metastasis 15% as calculated by Roach's formula * ECOG performance score 0-1 * Age ≥ 18 * History/physical examination within 2 weeks prior to registration * Able to sign informed-consent Exclusion Criteria: * Patients with previous diagnosis of cancer other than prostate cancer and non-melanoma skin cancer. * Evidence of distant metastases * Regional lymph node involvement * Previous radical surgery (prostatectomy), cryosurgery, or HIFU for prostate cancer * Previous pelvic irradiation, prostate brachytherapy, or bilateral orchiectomy * Previous hormonal therapy, such as LHRH agonists (e.g., goserelin, leuprolide) or LHRHantagonists (e.g., degarelix), anti-androgens (e.g., flutamide, bicalutamide), estrogens (e.g.DES), or surgical castration (orchiectomy) * Unstable angina and/or congestive heart failure requiring hospitalization, transmural myocardial infarction within the last 6 months, acute bacterial or fungal infection requiring intravenous antibiotics, chronic obstructive pulmonary disease exacerbation or other respiratory illness requiringhospitalization or precluding study therapy at the time of registration * Patients who have received prior chemotherapy.