The purpose of this study is to examine the safety and efficacy of an abbreviated course of preoperative radiation, given over five days, for patients with soft tissue sarcoma of the extremity, trunk or retroperitoneum. This is in contrast to standard preoperative radiation, which is given over 25 days.

Inclusion Criteria:

1. Histologically confirmed soft tissue sarcoma of the extremity, trunk or retroperitoneum.
2. Has been offered preoperative radiation and surgery as part of standard-of-care treatment
3. Age ≥ 18
4. KPS ≥ 70 or ECOG 0 to 2
5. Life expectancy ≥ 6 months
6. If a woman is of childbearing potential, a negative serum or urine pregnancy test must be documented.
7. Ability to understand and the willingness to personally sign the written IRB approved informed consent document.

Exclusion Criteria:

1. History of prior radiation to the area to be treated.
2. Active use of other anti-cancer investigational agents.
3. Planned use of concurrent chemotherapy, targeted therapy, or immunotherapy with radiation therapy (defined as the time interval starting 1 week before the first and last fraction of radiation therapy and surgery).
4. Pregnancy.