For localized soft tissue sarcomas (STS) of the extremities, limb-sparing or conservative surgery with perioperative radiotherapy (RT) is the standard of care. However, several challenges persist. Notably, there are exceedingly high rates of distant metastatic recurrence even after surgical resection and RT, and conventional fractionated radiotherapy has a prolonged duration (5-6 weeks). With advancements in RT technology, the gradual expansion of hypofractionated radiotherapy regimens enables significantly shorter treatment durations. Promising recent reports on 1-week hypofractionated RT regimens, such as the 5X5 Gy RT regimens, have demonstrated reasonable local control and acceptable toxicity in resectable STS.Addressing the challenge of distant metastasis, previous studies have indicated that AI regimens are expected to eliminate micrometastases and improve survival in patients with STS at a high risk of distant relapse. Therefore, the goal of this clinical trial is to investigate whether hypofractionated RT combined with a sequential chemotherapy（AI regimens）can enhance short-term treatment efficacy for extremity STS patients without compromising local control rates and increasing related toxicities

Inclusion Criteria:

1. Primary soft tissue sarcoma of the extremities, with one of the following characteristics: high grade, ≥5cm or deep tumor, the need for neoadjuvant radiotherapy was determined after multidisciplinary consultation.
2. Eastern Cooperative Oncology Group (ECOG) performance status 0 - 2.
3. Age 18-75 years old.
4. Histologic diagnosis of soft tissue sarcoma.
5. Can tolerate radiotherapy and AI regimen treatment.
6. The function of major organs is normal.

Exclusion Criteria:

1. There were no patients with gross tumors after unplanned mass resection in another hospital.
2. Patients with other comorbidities cannot use AI chemotherapy: drug allergy, active bleeding, ulcers, intestinal perforation, intestinal obstruction, uncontrollable hypertension, grade III-IV cardiac insufficiency (NYHA standards), severe liver and renal insufficiency ( Level IV) etc.
3. New malignant tumors within 5 years (except cervical carcinoma in situ or early cutaneous basal cell carcinoma).
4. Pathological types: nonpleomorphic rhabdomyosarcoma, Ewing sarcoma.
5. Soft tissue sarcoma curable by simple expansion.
6. Previous history of radiotherapy to the same site.
7. Combined with distant metastasis (M1) or lymph node metastasis (N1).
8. Have other severe medical comorbidities that preclude surgery or participation in the study.
9. Previous exposure to chemotherapy.