This is a phase II, multicenter, non-randomized study.

The main objective is to evaluate the treatment with hypofractionated radiation therapy in neo-adjuvant situations on wound healing in a population of aged patients (≥ 70 years old) or ≥ 65 years of age defined as "fragile" and treated for soft tissue sarcoma.

A maximum of 48 evaluable patients will be included in this study. The patients will receive an hypofractionated radiation therapy prior to conservative surgery.

Each patient will be followed for up to 3 years after the end of complete treatment (radiotherapy + surgery).

Inclusion Criteria:

1. Patient with histologically confirmed soft tissue sarcoma of the limbs or trunk.
2. Indication for neo-adjuvant or adjuvant radiotherapy.
3. Patient aged ≥ 70 years with a performance status ECOG ≤ 2 and/or aged 65 to 70 years with an ECOG of 2 and identified by the investigator as "fragile".
4. Patient affiliated to a Social Health Insurance in France.
5. Patient able to participate and willing to give informed consent prior performance of any study-related procedures.

Exclusion Criteria:

1. Retroperitoneal, ORL and visceral sarcomas.
2. Previous radiotherapy in the area.
3. Metastatic disease.
4. Concomitant or sequential chemotherapy.
5. Patient requiring total surgery (amputation).
6. Other cancer under treatment.
7. Any condition or pathology contraindicating MRI.
8. Any psychological, familial, geographic or social situation, potentially preventing the provision of informed consent or compliance to study procedure.
9. Patients included in another therapeutic interventional trial.
10. Patient who has forfeited his/her freedom by administrative or legal award or who is under legal protection (curatorship and guardianship, protection of justice).