Inclusion Criteria:
* Voluntary written informed consent, with the ability to fully understand and effectively communicate, before performance of any study-related procedure not part of normal medical practice, with the understanding that consent may be withdrawn by the subject at any time without prejudice to future medical care.
* Age \> 18 years
* Proven diagnosis of primary, resectable extremity/trunk wall STS with low-medium risk (Sarculator© predicted 10y-OS \> 60%)
* Measurable disease criteria (RECIST 1.1 and CHOI)
* ECOG: 0, 1 or 2 (if influenced by orthopedic condition and not by general status)
* No major contraindication to the planned radiotherapy or surgical treatment
* Active participation with adherence to requested treatment schedule and follow-up
* Female subject will undergo a negative pregnancy test
* Adequate bone marrow function (hemoglobin \> 9g/dL, Leukocytes \> 3000/mm³, platelets \> 100,000/mm³). Patients with plasma creatinine ≤ 1.6 mg/dL, transaminase (AST-SGOT, ALT-SGPT) ≤ 2.5 times the UNL; total bilirubin ≤ 1.5 time the UNL; alkaline phosphatase ≤ 2.5 times the UNL are acceptable. CRP, LDH, total protein and albumin must also be recorded.
* HBV and HCV serologies must be performed prior to patient inclusion. If hepatitis B surface antigen (HBsAg) is positive, further evaluation is required to exclude active viral replication (i.e., testing for hepatitis B e antigen \[HBeAg\] and HBV DNA). If either of these markers is positive, study inclusion is not recommended. In such cases, prophylactic treatment with lamivudine may be considered at the investigator's discretion. If a potential participant tests positive for anti-HCV antibodies, active infection must be ruled out through a qualitative HCV PCR test. If PCR testing cannot be performed, or if it confirms active infection, the patient will not be eligible for the study. Patients must be HIV-seronegative, with a CD4+ T-cell count greater than 400/mm³. Individuals with clinically significant immunodeficiency-either congenital or acquired-are not eligible for enrollment
Exclusion Criteria:
* Age \< 18y
* Soft tissue sarcomas (STS) originating at different sites (i.e., retroperitoneal, abdominal, pelvic, head and neck), gynecological sarcomas, as well as gastrointestinal stromal tumors (GISTs), desmoid-type fibromatosis and pediatric-type sarcomas (i.e., extraosseous Ewing sarcoma, embryonal/alveolar rhabdomyosarcoma, desmoplastic small round cell tumor) are excluded.
* Recurrent or metastatic condition or previous whoop-surgery for sarcoma (incisional biopsies are allowed if performed 6 months before referral).
* Unresectable tumors (with limb sparing surgery)
* Diagnosed oncological condition in the 5 years before enrollment (exceptions: Gleason \<6 prostatic adenocarcinoma; In-situ cervical cancer and melanoma; basal cell skin carcinoma radically treated)
* Prior radiation treatment to the site designated for planned surgery or radiotherapy, regardless of indication
* Any medical condition that can impair and reduce life expectancy to less than 2 years including but not limited to significant systemic diseases grade 3 or higher on the CI-CTCAE v5.0 scale, that limit patient availability, or according to investigator judgment may contribute significantly to treatment toxicity
* Uncontrolled bacterial, fungal, or viral infections-either systemic or localized at the site of planned surgery or radiotherapy
* Severe psychiatric disorder, psychological, familial, social or geographic circumstances that limit the patient's ability to comply with the protocol or informed consent.
* Patients who had participated in another clinical trial and/or had received any other investigational product in the last 30 days prior to inclusion
* Patients who had received any other treatment for the disease under study including chemotherapy, radiotherapy, surgery or any other treatment with curative intent. incisional biopsies are allowed if performed 6 months before referral.
* Inability to comply with the requested follow-up
* Women who are pregnant or breast-feeding
* Any condition that is unstable or could jeopardize the safety of the patient and their compliance in the study
* BMI \> 40 and BMI \< 18
