To investigate the safety and efficacy of preoperative moderately fractionated IMRT and concurrent Fluzoparib Hydrochloride for primary truncal or extremity soft tissue sarcoma.

To investigate the safety and efficacy of preoperative moderately fractionated IMRT and concurrent Fluzoparib Hydrochloride for primary truncal or extremity soft tissue sarcoma; To investigate the Quality of life and extremity function post-combination treatment; To study the mechanism of radio-sensitizing effects of Fluzoparib Hydrochloride for primary truncal or extremity soft tissue sarcoma; To assess the relationship between the MRI imaging, pathological findings and local control.

Inclusion Criteria:

• Age older than 18 years.
• Histology proven soft tissue sarcoma of truncal or extremity, deemed appropriate for preoperative radiotherapy and conservative surgery by multidisciplinary discussion.
• ECOG 0-3
• Histology reviewed by reference pathologist
• Lesion can be assessed
• Can tolerate radiotherapy and Fluzoparib (Fluzoparib group)
• Agree contraception.
• Informed consent: All patients must sign a document of informed consent indicating their understanding of the investigational nature and risks of the study before any protocol related studies are performed

Exclusion Criteria:

• No gross tumor post-resection in other center.
• Contraindications to Fluzoparib, including allergic to Fluzoparib, active bleeding, ulcer, enteric perforation, enteric obstruction, uncontrolled hypertension, Grade 3 to 4 cardiac insufficiency (per NYHA criteria), and severe hepatic or renal insufficiency (Grade 4), etc.
• Dermatofibrosarcoma protuberans(DFSP), Desmoids, etc.
• Benign histology
• Secondary cancer within 5 years (except cervical carcinoma in situ or early-stage skin basal cell carcinoma)
• STS can be cured by extensive operation alone.
• Previous irradiation to the same area
• radiological evidence of distant metastases
• Other contraindications, can't tolerate operation or other treatment needed in this study.