Palliative therapy can be thought of as "comfort care". It is treatment intended to maintain a good quality of life for patients in which long-term cancer control is not possible. Palliative radiation therapy can be used to control the symptoms associated with many localized tumors that cannot be treated by other methods (such as surgical removal). These symptoms include pain, bleeding, and decreased function. Radiation is usually combined with anti-inflammatory and pain medications to maximize the relief of cancer-related symptoms. The goals of palliative therapy are to provide symptom-relief, and not to increase survival time or cure the cancer. Radiation therapy is particularly useful in alleviating pain associated with tumors that are arising from, or invading into bone. About two thirds of patients have moderate to significant improvement, and the effects can last for a few weeks to several months. Decrease in symptoms can occur as quickly as several days after the first treatment, or it may take a few weeks before improvement is seen.
Palliative radiation involves delivering a few large doses of radiation over several weeks. The typical plan involves giving three treatments on days 0, 7, and 21 (in other words, two treatments a week apart, followed by a week of rest, and then a third treatment if indicated). In most cases, palliative radiation therapy is a one-time course of treatment and cannot be repeated. Each treatment requires light anesthesia because the patient must be completely still during the procedure—there is no pain or discomfort associated with delivery of the radiation. Your pet must have no food after 8 PM the night before each treatment (water is okay) to insure an empty stomach prior to anesthesia.
Patients are treated as outpatients, with each treatment requiring about 2-3 hours at the Veterinary Hospital of the University of Pennsylvania. This time includes preparation for anesthesia, treatment delivery, and recovery. The radiation is focused on the tumor, and the fur in this area will be clipped and pen marks used to outline the treatment area. A small area on a leg will also be clipped for an intravenous catheter (I.V.) used during the anesthesia. Your pet may be a little groggy or sedate for several hours after going home, and should be kept quiet and have limited food and water until fully recovered.
Side effects are minimal, and are limited to the area receiving radiation. They start after about three to four weeks from the first treatment and last for a few weeks. The radiated area will be pink to red and hairless and there may be some mild flaking or crusting of the skin. Treatments of these side effects include the use of topical medications and preventing your pet from licking, rubbing, or scratching at the treated area. Eventually the skin in this area will become very dark to black, and some sparse hair may regrow. Long term side effects (such as the risk of non-healing wounds) take many months or years to occur, and are typically not a problem because most patients undergoing palliative care have a life expectancy of less than one year due to their cancer.
To learn more about the specialty of veterinary radiation oncology, how to find a specialist and common questions; visit The American College of Veterinary Radiology.