• Age ≥ 18,

• Histological diagnosis of prostate malignancy cancer

• Cancer without loco-regional or distant metastasis (tumor assessment must comprise at least Pelvic MRI AND thoraco-abdomino-pelvic contrast-enhanced CT-Scan AND Bone Scintigraphy. (Note that additional assessment by PET-Scan is allowed as per investigator judgement),

• Unfavorable intermediate risk prostate cancer diagnosis defined by the NCCN Guidelines.

• One of the following criteria is sufficient to define an unfavorable intermediate risk prostate cancer:

⁃ Gleason = 7 (4+3)

⁃ ≥ 50% of thecore of biopsies need to be positive for adenocarcinoma

• If these criteria are not being identified, two or three of the following criteria are necessary to define unfavorable intermediate risk prostate cancer:

⁃ PSA value between 10-20 ng/ml

⁃ Gleason 7 (3+4) or 6

⁃ T2b (clinical or radiological) Note: patients with iT3a can be included only if gleason score is 6 and PSA less than 20 .

• Patients newly diagnosed with an unfavorable intermediate risk prostate cancer according to the protocol criteria or previously diagnosed with low risk (Gleason score \< 6, clinical stage \< T2a, and PSA\< 10) prostate cancer progressing to eligible risk disease according to the protocol criteria within 30 days before registration

• Patients must have a life expectancy of at least 5 years,

• Performance status ECOG ≤ 2,

• Patients without contra-indications to EBRT as per physician judgement,

• Patients with adequate organ function defined by all the following laboratory values

⁃ Available archived paraffin-embedded tumor sample for research purpose,

⁃ Patients with a social security in compliance with the french law,

⁃ Voluntary signed and dated written informed consent prior to any study specific procedure,

⁃ Men must agree to use an effective method of contraception throughout the treatment period and for one week after discontinuation of treatment.