Radiation Therapy

Radiation therapy is a local treatment option for many types of cancer. It plays a crucial role in the treatment of over 50% of human cancer patients. We are extremely fortunate to be able to provide this high level of care to our patients at VCA Encina Animal Hospital Specialists & Emergency.

For our purposes, the term radiation simply implies the transmission of packets or photons of energy through the air and into the body, much like x-rays. These photons cannot be seen or felt, nor are they radioactive. The photons pass through the body causing damage to the genetic material inside the cells being treated. This damage can lead to cell death within hours to weeks after the treatment is given.

Radiation therapy is administered in multiple treatments known as fractions. Each treatment is a 'fraction' of the total dose prescribed for a particular patient. Fractionation reduces the severity of side effects to normal cells, enhances the killing effect on cancer cells, and allows a higher total dose to be given. The dose prescription and fractionation protocol are not arbitrary. They are based on sound radiobiological principles and must be strictly adhered to in order to achieve the goals of therapy. This includes making sure your pet does not miss any treatments and completes the scheduled number of fractions.

Specifically the number of fractions will vary from 1 to 25 depending on the cancer, area being treated and treatment related goals. For each fraction patients will need to be placed under general anesthesia as they must remain motionless for correct tumor targeting. However the duration of anesthesia is only several minutes and because the act of radiation is painless, long acting pain medication is not required.

Radiation treatment protocols can be divided into two broad categories, definitive and palliative. The goal of definitive radiation is to deliver as much radiation as safely possible to achieve a maximum tumor cell kill. Palliative radiation, on the other hand is a much more conservative approach to radiation therapy where the goal is not necessarily to kill tumors cells but rather improve a pets quality of life. Depending on the location of the tumor and treatment goals, side effects from radiation therapy can occur. In general they are limited to the area that is being treated and range from very minimal to severe. Your veterinarian can treat your pet for side effects that may occur.