Trial Comparing Irradiation Plus Long Term Adjuvant Androgen Deprivation With GnRH Antagonist Versus GnRH Agonist Plus Flare Protection in Patients With Very High Risk Localized or Locally Advanced Prostate Cancer

The primary objective of the trial is to assess if GnRH antagonists in combination with external beam radiation therapy improve progression free survival (progression that can be biological, clinical, or death) compared to GnRH agonists in combination with external beam radiation therapy. Secondary objectives include: * documentation of effect of GnRH antagonists on clinically significant cardiovascular events in the subgroup of patients at high risk of such events at baseline; * documentation of side effects and quality of life, I-PSS and urinary tract infections; * assessment of relative treatment effect on secondary efficacy endpoints (clinical progression, time to next line of systemic therapy, time on therapy, overall and cancer specific survival) and on PSA at 6 months after end of RT.