Stereotactic Body Radiation Therapy (SBRT) for Unresectable Liver Metastases

This trial is studying Stereotactic Body Radiation Therapy (SBRT) — a very precise, high-dose radiation treatment — for people with liver metastases (cancer that has spread to the liver) from colorectal cancer, anal canal cancer, or gastrointestinal neuroendocrine tumors, who cannot be treated with surgery. **You may be eligible if...** - You have 1 to 4 liver metastases, each no larger than 5 cm across - Your liver metastases come from colorectal cancer, anal canal cancer, or gastrointestinal neuroendocrine tumors - Surgery is not suitable for you, or you are considered too frail for surgery - There is no cancer spread outside the liver (or any extrahepatic disease is being treated with curative intent) - Your blood counts and general health are acceptable **You may NOT be eligible if...** - You are receiving chemotherapy at the same time as radiation - You have had prior radiation to the upper abdomen - You are pregnant - You have liver cirrhosis or active hepatitis - You are on blood-thinning medication Talk to your doctor to see if this trial is right for you.