Standard Versus Radiobiologically-Guided Dose Selected SBRT in Liver Cancer

Inclusion Criteria: 1. Eligible patients include patients with any of the following: * Primary hepatobiliary cancer confirmed pathologically or, * Non-lymphoma liver metastases confirmed pathologically or, * Radiographic liver lesions most consistent with metastases, in a patient with known pathologically proven non-lymphoma cancer and a previously negative CT or MRI of the liver or, * Hepatocellular carcinoma diagnosed with vascular enhancement of the lesion consistent with hepatocellular carcinoma, and with an elevated AFP, in the setting of cirrhosis or chronic hepatitis. 2. ≤ 5 liver lesions measurable on a contrast-enhanced liver CT or MRI performed within 90 days prior to study entry. 3. Primary liver lesion or liver metastases measuring ≤ 25 cm. 4. Extrahepatic cancer is permitted if liver involvement is judged to be life-limiting 5. No contraindications to radiotherapy 6. Patient must be judged medically or surgically unresectable 7. Zubrod Performance Scale = 0-3 8. Age \> 18 9. Systemic treatment including multikinase inhibitors and immunotherapy are allowed. Multikinase inhibitors must be held 2 weeks prior to radiation and may be restarted 1 week post radiation. 10. Previous liver resection or ablative therapy is permitted 11. Chemotherapy must be completed at least 2 weeks prior to radiation therapy and not planned to be administered for at least 1 week (for anthracyclines at least 4 weeks) after completion of treatment. 12. Life expectancy \> 6 months. 13. Women of childbearing potential and male participants must practice adequate contraception. Exclusion Criteria: 1. Severe cirrhosis or liver failure defined as Child Pugh \>B7 2. Prior radiotherapy to the region of the study cancer that would result in overlap of radiation therapy fields 3. Severe, active co-morbidity, defined as limiting the patient's life to less than 6 months 4. Active hepatitis or clinically significant liver failure. Treated hepatitis is permitted. 5. Pregnancy, nursing women, or women of childbearing potential, and men who are sexually active and not willing/able to use medically acceptable forms of contraception; this exclusion is necessary because the treatment involved in this study may be teratogenic.