Radiation therapy is not a primary treatment for colon cancer, although it is used more frequently in patients with rectal cancer. In patients with colon cancer, radiation therapy may be used as a neoadjuvant therapy to help shrink a tumor and make it easier to remove surgically. It also may be used after surgery as an adjuvant therapy in patients with tumors invading abdominal organs. Occasionally, intraoperative radiation therapy may be used to address any cancer cells left behind during surgery, or it may be used in combination with chemotherapy in patients who can't tolerate surgery. It may also be used palliatively to reduce intestinal blockage, bleeding, or pain, or to treat cancer that has metastasized to the bones or brain. To learn more about how radiation therapy is used in patients with rectal cancer, tap the RT in Rectal Cancer button.