Patients with extremity soft tissue sarcoma (STS) are at high risk of recurrence. Pre-operative radiotherapy is used to increase the safe removal of tumors and improve local control in these patients. Increasing the preoperative radiotherapy dose with standard techniques might lead to normal tissue toxicity and postoperative wound complications.

GRID radiation therapy is a technique that may increases radiation dose with minimal added toxicity. It is hypothesized that GRID radiation dose will improve tumor response without increasing post-operative wound complications. While GRID has been used in many patients, there have been few formal studies to evaluate the safety and efficacy of the technique. In this study, a single priming dose of GRID will be administered to subjects with high-risk extremity soft tissue sarcoma prior to standard radiotherapy and tumor resection to determine the safety and clinical efficacy of the GRID dose. This single-arm pilot study will assess the safety of spatially fractionated grid radiation therapy (GRID) on 20 subjects with resectable extremity soft tissue sarcoma, followed by standard-of-care conventional radiotherapy (XRT) and tumor resection.

In order to participate in this study a subject must meet all of the eligibility criteria outlined below.

Inclusion Criteria:

1. Written informed consent was obtained to participate in the study and HIPAA authorization for the release of personal health information. Subjects are willing and able to comply with study procedures based on the judgment of the investigator.
2. Age ≥ 18 years at the time of consent.
3. Eastern Cooperative Oncology Group (ECOG) Performance status of 0 - 2 (Karnofsky Performance Status equivalent of 50 - 100).
4. Histological or cytological evidence/confirmation of extremity soft tissue sarcoma as determined by core-needle biopsy or excision biopsy. If the diagnostic tissue is not available or sufficient to perform correlative studies, must be willing to provide the mandatory pre-treatment core-needle biopsy. In some cases of extremity STS, subjects undergo an attempted surgical resection for a presumed benign condition and the specimen reveals malignancy. Such subjects are allowed so long as a complete, oncologic, resection was not performed/attempted and there is ≥ 5 cm of the remaining primary tumor.

Exclusion Criteria:

Subjects meeting any of the exclusion criteria listed below at baseline will be excluded from the study.

1. Subjects who have received prior radiotherapy to the tumor site.
2. Subjects who have undergone complete tumor resection of the primary tumor or who have developed tumor recurrence after resection.
3. History of serious or non-healing wound, ulcer, or bone fracture in the treatment limb within the last 5 years.
4. History of clinically significant lymphedema in the treated limb.
5. History of lupus, scleroderma, Sjogren's syndrome, Ehlers-Danlos syndrome (any type), or other collagen vascular disease that may pose a relative contraindication, due to increased risk of skin or soft tissue toxicity, with radiation.