Inclusion Criteria:

• * Oligometastatic or primary malignancy planned for proton SBRT. Disease site should be biopsy-proven primary disease of solid tumor histology with the exception of Hepatocellular carcinoma (HCC). HCC does not need to be biopsy proven if imaging and clinical findings are consistent with the diagnosis.
• * Must be deemed medically fit for proton SBRT by the treating physician.
• * Prior radiation therapy is allowed.
• * At least 18 years of age.
• * Karnofsky ≥ 70%.
• * Because radiation therapy is known to be teratogenic, 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, or a male suspect he has fathered a child, s/he must inform the treating physician immediately.
• * Ability to understand and willingness to sign an IRB approved written informed consent document.

Exclusion Criteria:

• * Histology of small cell carcinoma. Mixed histologies with a predominantly small cell component are also exclusionary.
• * Patients with a prior or concurrent malignancy whose natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen are eligible for this trial.
• * Medical contraindication to proton therapy or any other condition that in the opinion of the treating radiation oncologist, renders the patient unfit for SBRT
• * 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. Women of childbearing potential must have a negative serum or urine pregnancy test within 14 days of study entry.