This study targets non metastatic prostatic locally-advanced adenocarcinomas which are at high risk of both local progression and metastases. The standard treatment of these tumours associates external beam radiation therapy (EBRT) and 3 years of androgen deprivation (AD) with LH-RH analogue. In the absence of AD and mainly when prostate specific antigen (PSA) is \>10 ng/ml, several randomized studies have shown that high doses of EBRT increase biochemical control. Nevertheless, escalating the doses of radiation significantly increases the risk of rectal and/or urinary toxicities. In order to lower the toxicity of irradiation in locally-advanced prostate cancers, and to improve the quality of life of patients, this study aims at decreasing the volume of irradiated healthy tissues. To carry out this objective, we will use a double strategy:
* Limiting the target volume to prostate only by removing seminal vesicles at the time of lymph node dissection,
* Using a technique of high-precision radiation combining Intensity Modulated Radiation Therapy (IMRT) and Image-Guided Radiation Therapy (IGRT).
Based on the literature, we may assume a toxicity rate of 30% during the three years of hormonotherapy with standard treatment (i.e. without removing seminal vesicles). We make the hypothesis of a 20% absolute reduction of toxicity with our protocol.
