Radiation Therapy - Associated Side Effects
Acute radiation side effects occur in rapidly proliferating tissues within the irradiated field. The acute side effects seen with a full course of radiation therapy typically start during, or soon after, the course of therapy. Although acute effects may cause temporary discomfort, they are self-limiting with most resolving 3-4 weeks after therapy. Advances in radiation therapy technology, such as the 6 MV Varian EX linear accelerator and 120-leaf multi-leaf collimator (MLC) at Purdue, are able to decrease the severity, or even eliminate acute effects. Mucositis (inflammation of the mucous membranes) and desquamation (shedding of the outer skin layer) are common acute side effects of therapeutic radiation. Treatment options are available to help alleviate the temporary discomfort associated with these side effects. Your veterinarian will discuss potential side effects (and the course of their treatment) with you prior to treatment. These side effects may require home care of the patient for up to a few weeks after therapy.
Late effects occur in slowly or non-proliferating tissues within the irradiated field that occur months to years after radiation therapy. Late effects which could be progressive and irreversible, are the dose limiting complication of radiation therapy. Late effects are highly dependent on size of fractionation (larger dose per fraction = greater complications) and the volume of normal tissues irradiated. Fibrosis (formation of a scar), ulcers, hyperpigmentation (darkening of the skin), necrosis (tissue death most often related to decreased blood flow to that tissue), atrophy, cataract formation, and neuropathy (damage to nerves of the central nervous system) are common late side effects of radiation therapy. Late effects are rare. Access to advanced technologies such as IMRT has improved our ability to spare normal tissues and avoid late side effects.