Intermittent Hormonal Therapy With Leuprorelin and Flutamide in the Treatment of Stage D2 or TxNxM1b,c

This is an open, comparative, randomized (1:1), multicenter, European (France, Germany, Czech Republic, Slovakia and Bulgaria), Phase 2B study on parallel groups of patients presenting with metastatic prostate cancer (stage D2 or Tx Nx M1 ≠ M1a), with a PSA level ≥ 5-fold higher than normal (that is PSA ≥ 20 ng/mL, as quantitated by the Hybritech radioimmunoassay) which return to normal within 6 months after the initiation of total androgen blockade therapy with leuprorelin 3.75 mg SR and flutamide. It will involve 314 preselected patients. A minimum of 180 eligible patients are required for this study. Selected patients will be randomized centrally in two parallel groups at study entry. This phase 2B study will enable evaluation of a high number of patients by direct comparison with conventional administration. The study comprises of two therapeutic phases: * A 6 month induction phase with complete androgen suppression by leuprorelin 3.75 mg SR and flutamide. This phase involves patients meeting the preselection criteria. * A data processing run per complete androgen suppression according to two methods, continuous or intermittent, for the patients satisfying the criteria of selection of the study and which will thus be randomized. The selected patients will be randomized in two parallel groups at the time of inclusion: * Group A patients will receive a continuous complete androgen suppression therapy by leuprorelin 3.75mg SR and flutamide, until the appearance of signs of disease progression or study end. * Group B patients will receive an intermittent complete androgen suppression therapy by leuprorelin 3.75 mg SR and flutamide, until the study end or the appearance of signs of disease progression under treatment. Group A patients will be routinely followed-up on a 3-month basis until there are signs of disease progression. Group B patients (intermittent therapy) will be monitored every 3 months during on-treatment periods under the same conditions as described for group A. The 3-month clinical follow-up will be same during off-treatment periods, but if PSA increases to ≥10 ng/mL the patient must be contacted to schedule a prompt special visit in order to reinstitute hormonal therapy. Subsequent visits will be scheduled on a 3-month basis from the time of the special visit. Special visits will be the same as routine consultations, except that the laboratory tests will not be redone. When on-therapy tumor progression will be documented, every 6 months the investigators will note all treatments administered to patients until death (while specifying the cause of death).