Outside the setting of well-designed prospective clinical studies, the current standard preoperative RT should be a conventionally 1.8-2 Gy fractionated regimen to a total dose of 50 Gy in 5-6 weeks. However, given the vast diversity of sarcoma subtypes, it is also unlikely to assume a uniform therapeutic management to be optimal for all sarcomas alike. Other than 2 Gy fraction sizes and/or 50 Gy total dose series have been investigated in the past and should be further exploited in the future, but the practical implementation in humans is hampered by the rarity of the disease.

The current systemic treatment of sarcomas consists of both the older cytotoxic chemotherapies and the newer targeted therapies like tyrosine kinase inhibitors. But it is hard to predict which patients will respond to which specific systemic treatment. This leads to worse prognoses and unnecessary toxicity for sarcoma patients. Despite the fact that the number of sarcoma patients in current studies is too small with a mix of different subtypes, some subtypes show a better response than other subtypes. This platform may form the basis for preclinical translational investigations with radiotherapy and various systemic treatments.

Inclusion Criteria:

• Histologically confirmed diagnosed (non-) metastatic intermediate to high grade STS
• Local recurrences are allowed
• Age ≥ 18 years
• Able and willing to undergo tumour biopsies or tumour sampling during surgery
• Localization of sarcoma enables safe biopsy or surgery
• Written informed consent

Exclusion Criteria:

• Known coagulation disorder and/or anticoagulant medication in as far it might interfere with a safe biopsy procedure (to the discretion of the treating physician and attending radiologist)
• Any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule; those conditions should be discussed with the patient before registration in the study