Palliative Lattice Stereotactic Body Radiotherapy (SBRT) for Patients With Sarcoma, Thoracic, Abdominal, and Pelvic Cancers

Inclusion Criteria:

* Histologically or cytologically confirmed sarcoma (including extremity), thoracic cancer (including esophageal), abdominal cancer (including retroperitoneal sarcoma), or pelvic cancer.
* Planning to undergo palliative radiotherapy to a lesion ≥ 4.5 cm as measured with radiographic imaging or with calipers by clinical exam.
* ECOG performance status ≤ 2
* At least 18 years of age.
* Radiotherapy is known to be teratogenic. For this reason, women of childbearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control, abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she must inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of the study, and 6 months after completion of the study
* Ability to understand and willingness to sign an IRB approved written informed consent document

Exclusion Criteria:

* Prior high-dose radiotherapy that overlaps with any planned site of protocol radiotherapy. Patients where the Lattice SBRT fields may overlap with the low dose (\<10 Gy) region of prior radiotherapy treatments are eligible and may be treated if this is determined to be safe by the treating physician.
* Patients with tumors in need of urgent surgical intervention, such as life-threatening bleeding or those at high risk for pathologic fracture.
* Currently receiving any cytotoxic cancer therapy regimens or VEGF inhibitors that will overlap with the Lattice SBRT administration.

  \*Cytotoxic chemotherapy and VEGF inhibitors prior to radiotherapy or planned after radiotherapy delivery are allowed at the discretion of the treating radiation oncologist. This includes continuing a treatment plan which was initiated prior to the start of radiotherapy. A 2-week washout is recommended, but not required.
* Pregnant. Women of childbearing potential must have a negative pregnancy test within 20 days of study entry.
* Patients with HIV are eligible unless their CD4+ T-cell counts are \< 350 cells/mcL or they have a history of AIDS-defining opportunistic infection within the 12 months prior to registration. Concurrent treatment with effective ART according to DHHS treatment guidelines is recommended. Recommend exclusion of specific ART agents based on predicted drug-drug interactions (i.e. for sensitive CYP3A4 substrates, concurrent strong CYP3A4 inhibitors (ritonavir and cobicistat) or inducers (efavirenz) should be contraindicated).