RATIONALE: Androgens can cause the growth of prostate cancer cells. Antihormone therapy, such as triptorelin, may lessen the amount of androgens made by the body. Radiation therapy uses high-energy x-rays to kill tumor cells. It is not yet known whether giving triptorelin and radiation therapy soon after surgery or later after surgery is more effective in treating prostate cancer.

PURPOSE: This randomized phase III trial is studying giving triptorelin and radiation therapy soon after surgery to see how well it works compared with giving them later after surgery in treating patients who have undergone surgery for intermediate-risk stage III or stage IV prostate cancer.

OBJECTIVES:

Primary

• Compare the efficacy, in terms of event-free survival at 5 years, of immediate radio-hormonal therapy immediately after prostatectomy for tumor pT2, R1, pN0, or pNx versus radio-hormonal therapy at biochemical relapse.

Secondary

• Compare the overall survival of patients treated with these regimens.
• Compare the metastasis-free survival of these patients.
• Compare the acute and late toxicities of these regimens in these patients.
• Compare the quality of life of patients treated with these regimens.
• Compare the functional dependence of patients over 75 years old.

OUTLINE: Patients are randomized to 1 of 2 treatment arms.

• Arm I (delayed treatment): Patients receive triptorelin intramuscularly on day 1 and then 3 months later. Patients also undergo conformal radiotherapy daily, 5 days a week, for 7 weeks. Treatment begins at biochemical relapse (PSA is more than 0.2 ng/mL) and before PSA is more than 2 ng/mL.
• Arm II (immediate treatment): Patients receive treatment as in arm I, but treatment begins within 6 months after surgery.

After completion of study treatment, patients are followed for up to 5 years.

Inclusion criteria:

1. Patient must have undergone curative surgery for a localized adenocarcinoma of the prostate
2. pT3a, pT3b (or pT4 by reaching the bladder neck), or R1 disease (stage III or IV)
3. PSA ≤0.1 ng/mL after prostatectomy (confirmed at 1 month)
4. May receive treatment within 6 months after surgery
5. Positive margins (tumoral glands in contact with contour ink) on the surgical specimen
6. pN0 or pNx (lymph nodes resected during negative prostatectomy or lymph nodes not resected)
7. No current clinical or biochemical progressive disease
8. Life expectancy ≥10 years
9. Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
10. Patient must be affiliated to the social security system
11. Patient must have received the information sheet and signed the consent form

Exclusion criteria:

1. Patient with prostate cancer other than adenocarcinoma
2. Gleason score ≥8 and with seminal vesicles involved
3. pN1 disease (Histologically confirmed nodal invasion during initial lymph node resection)
4. pT2 disease
5. Prior surgical or chemical castration
6. Prior hormonal therapy
7. Prior radiotherapy within 3 months after radical prostatectomy
8. Prior pelvic radiotherapy
9. No history of cancer (except basal cell skin cancer) within 5 years of surgery
10. No known severe hypertension uncontrolled by appropriate therapy (≥160 mm Hg systolic and/or ≥90 mm Hg diastolic)
11. Known hypersensitivity to gonadotropin-releasing hormone or its analogs
12. Contraindication to intramuscular injection
13. Concurrent participation in another interventional study
14. Patients under protective custody or guardianship, unable to comply with the specific requirements of the study or unable to understand the purpose of the study