Goals for Radiation Therapy
Definitive Radiation Therapy
Definitive radiation is administered with the goal of achieving long-term control of the disease. Depending on the part of the body where the tumor is located, most veterinary patients treated with definitive protocols are treated over a three to four week period. This allows the total radiation dose to be delivered as a number of smaller doses or “fractions”. Fractionation makes it possible for normal cells to repair themselves of radiation damage between treatments. Small tumors can be treated by radiation therapy as the primary therapy for long-term control. We can also use radiation therapy in conjunction with surgery for many tumors. Depending on the location, acute, temportary side effects may occur. These side effects normally heal quickly and are generally resolved within three to four weeks after the course of radiation therapy is completed. Advances in technology, such as IMRT, are helping to minimize acute effects.
Palliative Radiation Therapy
The goal of palliative therapy is to relieve pain and other clinical signs to improve and help maintain a patient's good quality of life with minimal side effects. The goal of palliative radiation therapy is to shrink or stabilize the growth of the tumor and avoid significant side effects. Most palliative radiation therapy protocols use fewer fractions, a higher dose per fraction, and a lower total dose compared to definitive protocols. These protocols may involve weekly treatments or treatments given over the course of a few days. Palliative protocols are often used when the patient has advanced cancer with metastasis (tumor spread to other locations), or some other critical health condition that would limit life expectancy. Palliative therapy rarely causes acute side effects. Palliative therapy may be recommended for, but is not limited to, tumors causing bone pain, masses occupying a large space and causing obstruction or discomfort, tumors compressing the spinal cord, and invasive nasal or oral tumors.