Retro peritoneal liposarcomas are rare (less than 15% of sarcomas) whose prognosis is locoregional. In the treatment of retroperitoneal liposarcomas main prognostic factor is the quality of the surgical resection. The effect of radiotherapy combined with surgery is uncertain and until now limited perhaps because of limited prescribed doses (of the order of 45Gy to 50Gy) due to high risk of organ toxicity nearby.~Two elements can overcome these difficulties:~Preoperative radiotherapy made rather than Postoperatively, the tumor in place back the gastrointestinal tract and reducing toxicity,~The contribution of conformal radiotherapy techniques with intensity modulation (IMRT). The helical tomotherapy is an innovative equipment radiotherapy to make conformational radiotherapy modulation intensity and is particularly suitable for irradiations precision (imaging mode associated with daily scanner) in large complex volumes. Increasing doses (increase of the prescribed dose to 54 Gy, thus potentially curative), the helical tomotherapy should allow to improve the efficacy of radiotherapy.
Retro peritoneal liposarcomas are rare (less than 15% of sarcomas) whose prognosis is locoregional.~In the treatment of retroperitoneal liposarcomas main prognostic factor is the quality of the surgical resection. The effect of radiotherapy combined with surgery is uncertain and until now limited perhaps because of limited prescribed doses (of the order of 45Gy to 50Gy) due to high risk of organ toxicity nearby.~The helical tomotherapy is an innovative equipment radiotherapy to make conformational radiotherapy modulation intensity and is particularly suitable for irradiations precision (imaging mode associated with daily scanner) in large complex volumes. Increasing doses (increase of the prescribed dose to 54 Gy, thus potentially curative), the helical tomotherapy should allow to improve the efficacy of radiotherapy.