[Target volume in soft tissue sarcoma of the extremities]

Soft tissue sarcoma is a rare entity and heterogeneous disease and its management therefore requires an experienced multidisciplinary team in an expert center. Standard treatment for grade 2 and 3 sarcomas is a conservative, extended surgery planned according to the results of the biopsy, and radiotherapy usually administered postoperatively (or pre-operatively). The indications for preoperative radiotherapy are discussed in a multidisciplinary meeting for locally advanced tumours. The definition of target volumes for conformal radiation therapy requires a good knowledge of the patient record, radioanatomy, as well as a careful reading of surgical and histological reports. The definitions of target volumes combine anatomical and geometrical approach. The gross tumour volume is the visible tumour on MRI preoperatively. The corresponding clinical target volume is defined by a larger longitudinal automatic extension than the radial extension. It is manually corrected taking into account the anatomical barriers to tumour spread. The planning target volume is a concentric automatic margin that may vary from one institution to another, depending on the immobilisation devices and verification of repositioning. Innovative radiotherapy techniques may be used to reduce the size of the margins around target volumes and better protect the organs at risk.