Surgery Combined With Intensity Modulated Radiation Therapy - Image-Guided Radiation Therapy (IMRT-IGRT) in Locally-advanced Prostate Cancers

Overview

Standard treatment of locally-advanced prostate cancers consists in the association of radiotherapy of prostate and seminal vesicles (SV) and androgen deprivation (AD) for 3 years. This treatment is usually preceded by pelvic lymphadenectomy to assess the possible extension to lymph nodes of prostatic cancer and to avoid irradiating the pelvis in case of no lymph node involvement. However, radiotherapy leads usually to about 30% of grade ≥2 risk of bladder and/or rectal toxicity. This risk particularly depends on the radiation volume. In the aim of lowering the toxicity, the treatment in this study will associate: * pelvic lymph node dissection and resection of seminal vesicles, allowing decreasing the radiation target volume to the prostate only (and not to irradiate the SV); * a high-precision radiotherapy technique combining Intensity Modulated Radiation Therapy (IMRT) and Image-Guided Radiation Therapy (IGRT).

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.