This study aims to investigate the value of 68Ga-grazytracer in predicting the efficacy of immunotherapy for advanced soft tissue sarcomas.

The investigators will number all participants, create a medical record file, and record their basic information (gender, age) as well as contact information and medical history information. All participants will undergo a 68Ga-grazytracer PET/CT after 3 cycles of immunotherapy to evaluate response. The imaging response measurements will be compared with the histopathological or clinical assessment results as gold standard.

Inclusion Criteria:

1. Pathological and clinical diagnosis of advanced soft tissue sarcomas, pathological types include: fibrosarcoma, liposarcoma, undifferentiated pleomorphic sarcoma, epithelioid sarcoma, rhabdomyosarcoma, synovial sarcoma, alveolar soft-part sarcoma, leiomyosarcoma, clear cell sarcoma, malignant schwannoma, angiosarcoma.
2. Consider immunotherapy or combined immunotherapy based on clinical judgement.
3. Signed and dated informed consent form.
4. Commitment to comply with research procedures and co-operation in the implementation of the full research process.
5. Aged 6-80 years old.

Exclusion Criteria:

1. Patients with serious illnesses that researchers consider unsuitable for participation in this clinical study. Such as severe heart and lung failure, severe bone marrow suppression, severe liver and kidney dysfunction, etc.
2. Intestinal perforation, complete intestinal obstruction
3. Pregnant women and women who may be pregnant, women who are breastfeeding.
4. Non-compliant person

Inpatients and outpatients at Ruijin Hospital who meet the inclusion criteria.