Low accrual

In light of this new technology and preliminary findings of low toxicity of online, adaptive, magnetic resonance (M)-guided stereotactic radiation on a single arm prospective study, the investigators propose to compare this technique to online MR-guided stereotactic body radiation therapy (SBRT) without adaptation. Online plan adaptation increases treatment times for patients and comprises an increased burden on technical and clinical staff. Although preliminary trial results are encouraging, it remains unclear if the dosimetric benefits of online-adaptive planning studies will translate to measurable improvements in clinical outcomes that merit its routine use. In our preliminary study, plan adaptation was most often required when tumors were adjacent to the gastrointestinal tract (the esophagus to the sigmoid colon), as those structures were most commonly the dose-limiting structures and were noted to change in location on a day-to-day basis. For these reasons, abdominal disease sites have historically highlighted the limitations of SBRT. Specifically, the investigators will enroll patients with oligometastatic or unresectable primary disease of the non-liver abdomen to a randomized, prospective trial.

Patients will be randomized to one of two treatment arms, in which they will receive either online-adaptive, MRI-guided SBRT or non-adaptive MRI-guided SBRT. Both patient groups will undergo MRI simulation and MRI treatment localization with online MR monitoring and/or gating. All patients will be treated in five fractions over one to two weeks. By adhering to strict normal tissue constraints, the investigators expect toxicity to be within the current standard of care for the non-adaptive arm, with reduction in toxicity in the arm of patients who undergo adaptation based on daily anatomic changes.

Inclusion Criteria:

• Oligometastatic disease or unresectable primary abdominal malignancy with biopsy-proven primary disease histology of solid tumor categorization. Patients with a diagnosis of hepatocellular carcinoma do not require a biopsy.
• No more than three progressive sites of disease, with at least one of the disease sites to be deemed suitable for treatment with MRI-guided, online adaptive SBRT to the non-liver abdomen as per radiation oncology evaluation.
• Must be treated per protocol to lesion(s) of a single abdominal site that can reasonably be encompassed within a single treatment field. Treatment of additional site(s) outside of the abdomen while the patient is on trial is acceptable.
• The treated lesion must be within 2 cm of the abdominal gastrointestinal tract (abdominal esophagus to sigmoid colon) on the basis of cross sectional imaging study such as computed tomography (CT), positron emission tomography (PET)/CT, or MRI.
• Must be deemed medically fit for SBRT by the treating physician.
• At least 18 years of age.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• Must have completed any systemic therapy at least one week prior to planned start of SBRT (two weeks preferred), and must have no plans to initiate systemic therapy for at least one week following end of SBRT (two weeks preferred).
• 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.
• Able to understand and willing to sign an Institutional Review Board (IRB) approved, written informed consent document (or that of legally authorized representative, if applicable).

Exclusion Criteria:

• Primary disease of hematologic origin, lymphoma, or small cell cancer.
• Past history of external beam radiotherapy within the projected treatment field of any of the disease sites to be treated by MRI-guided, online adaptive SBRT.
• Currently receiving any other investigational agents.
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, or cardiac arrhythmia.
• Pregnant and/or breastfeeding. Patient must have a negative pregnancy test within 14 days of study entry.
• Medical contraindication to undergoing MR imaging.