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.