Phase IIIb, Open-label, randomized, controlled multi-centre study. Induction therapy phase for 6 months where all subjects receive 2 ELIGARD depot injections. Those subjects with hormone responsive prostate cancer will be randomized and will receive either intermittent or continuous ELIGARD treatment for 36 months. Following this treatment period, subjects will enter a long-term follow-up period for 48 months.

Inclusion Criteria:

At study entry (visit 1):

• Written informed consent
• Male subjects aged >=18 and <80 years old
• Locally advanced (stage T3 or T4) prostate cancer or Relapsing prostate cancer following radical prostatectomy or,Relapsing prostate cancer following radiotherapy
• Gleason score of >=6
• ECOG performance status of 0-2.
• Life expectancy at least 5 years

At randomization (visit 4):

• Two successive decreasing serum PSA levels <=1 ng/ml

Exclusion Criteria:

At study entry (visit 1):

• Any suspected second primary tumors
• Evidence of metastatic disease
• Other malignancy within the last 5 years except
• Acute spinal cord compression, uni- or bilateral ureteric obstruction
• Any concurrent biological response modifier therapy
• Concurrent chemotherapy
• Less than 1 year since any prior neoadjuvant or adjuvant hormonal therapy
• Less than 6 months since prior 5-alpha reductase inhibitor treatment
• Other concurrent hormonal therapy
• Any concurrent radiotherapy
• Testosterone at screening <= 1.7 mM or 50 ng/dL
• Clinically significant elevation of serum creatinine or liver enzymes
• Hypersensitivity to GnRH or other GnRH analogues or leuprorelin acetate
• Hypersensitivity to CASODEXâ 50 mg.