Prostate-cancer Treatment Using Stereotactic Radiotherapy for Oligometastases Ablation in Hormone-sensitive Patients

DIAGNOSIS AND INCLUSION CRITERIA:

1. Histologically proven adenocarcinoma of the prostate (any T stage, Gleason score, or prostate specific antigen (PSA) level);

2. Defined as M1 based on the presence of at least one bone metastasis;

3. Diagnostic workup including functional imaging (F or C-Choline-PET/CT or prostate specific membrane antigen (PSMA) PET/CT or whole body MRI) - done prior to the start of hormonal therapy;

4. With up to 5 asymptomatic or paucisymptomatic metastatic sites including at least one bone +/- pulmonary lesion +/- nodal mestastases. Are counted as a "separate" metastatic site :

• each bone lesion, whatever the location (including pelvic localization), except if two lesions show hyperfixation in the same bone and are located < 1cm from each other they can be counted as one lesion

• each node or nodal area located outside the true pelvis with a small diameter of 1cm or greater or with univoqual abnormal function imaging (PET Scan hyperfixation or hypersignal in whole body MRI); if multiple nodes are in close vicinity (<1cm distance between them and <4cm in total distance including the nodes, amenable to one SBRT treatment) they can be counted as one lesion

• and patients with lung metastasis can be included

5. Patients with a previous prostatectomy or radiotherapy to the prostate and/or pelvic lymph nodes are eligible provided they have no active disease within the irradiated areas, based on functional imaging findings;

6. Age ≥18 years;

7. Eastern Cooperative Oncology Group (ECOG) ≤2;

8. Suitable for long term anti androgen therapy;

9. Patient not suitable for docetaxel or abiraterone can be included;

10. Patient that have started long term hormonal therapy are eligible if hormonal therapy has been initiated less than 2 months before randomization;

11. Patients must agree to use adequate contraception methods for the duration of study treatment and for 6 months after completing treatment;

12. Patient must have received the information sheet and signed the consent form;

13. Patients must be willing and able to comply with the protocol for the duration of the study including scheduled visits, treatment plan, laboratory tests and other study procedures;

14. Patient must be affiliated to the social security system.

NON-INCLUSION CRITERIA:

1. Patient with more than 5 metastatic sites;

2. Patient with isolated Rib hyperfixation on functional imaging without a clear correlate on morphological imaging;

3. Patient with metastatic sites other than bone, lymph nodes or lung;

4. Metastases not amenable to radiotherapy treatment with high/curative doses by multidisciplinary meeting [i.e. SBRT as per protocol or curative doses using moderate hypofractionation (55-60Gy/20) or conventional fractionation (≥74 Gy)] (e.g. gross epidural involvement, involvement of three contiguous vertebral bodies, major soft tissue involvement, and previous radiation treatment);

5. Metastases requiring immediate treatment due to significant pain (use of opioid medication), or at risk of fracture or neurological deficit;

6. Prior radiotherapy or focal ablative treatment (cryotherapy, radiofrequency ablation,...) to metastatic lesions;

7. Patients previously treated by Hormonotherapy with castrate testosterone level <50 ng/dL or ≤0.50 ng/mL or 1.73 nmol/L prior use of ADT;

8. Prior invasive (except non-melanoma skin cancer) malignancy unless disease-free for ≥5 years;

9. Contra-indication to MRI (needed for spinal SBRT);

10. Persons deprived of their liberty or under protective custody or guardianship;

11. Patients unwilling or unable to comply with the medical follow-up required by the trial because of geographic, familial, social, or psychological reasons;

12. Participation in another therapeutic trial within 30 days prior to randomization.