What are the most common reasons radiation therapy is recommended for patients?

Invasive cancers can be difficult to remove surgically if they are located in confined spaces next to important normal tissues, such as blood vessels and nerves. Radiation therapy is often recommended in such areas where complete surgical removal of the tumor is not possible without disruption of normal function or significant change in appearance. A good example is a tumor located on a distal limb. Although amputation is an option generally to cure such a tumor, at times such an aggressive approach may not be necessary. Surgical removal of most of the tumor (‘debulking") followed by radiation can potentially provide long term control with the added benefit of maintaining the limb function.

Radiation therapy can also be used to control pain and inflammation. "Palliative" radiation is not intended to control the cancer. Importantly, such therapy is prescribed to alleviate pain and discomfort. Such patients inevitably succumb to cancer progression, but this approach can offer quality time and relief.

What happens during the process of therapy and what is a typical radiation treatment schedule?

Radiation treatments are typically performed on each patient on a daily basis (Monday through Friday) for a period of 3-4 weeks. These are outpatient appointments, in which your pet is dropped off in the morning and generally will be ready to be picked up in the afternoon. We ask that you not feed your pet after 10 pm the evening prior to each appointment. An intravenous catheter will be placed for administration of fluids and anesthetic medications and removed prior to dismissal from the hospital. The treatment is performed with your companion under a brief anesthesia to ensure accurate placement of the dose of radiation. Specific recommendations and concerns about your pet’s care will be provided at dismissal.

Will chemotherapy and/or surgery be a part of the treatment plan?

A comprehensive treatment plan will be formulated prior to the start of any therapy for your pet. It is important that we work with you to ensure an understanding of the goals of cancer treatment, provide realistic expectations of therapy and address any challenges concerning quality of life and home care. The application and timing of radiation therapy, surgery and chemotherapy (if applicable) is unique for each and every patient.

What about side effects of radiation therapy?

Side effects are a critical aspect of any cancer therapy. In radiation therapy, such concerns are divided into two categories: "acute" and "late" side effects. Our goal is to minimize these effects while providing the best chance for great quality of life, long term tumor control and survival.

"Acute" side effects will occur during the weeks in which therapy is administered and generally will continue for 1-3 weeks afterwards. These changes are occurring to the normal tissue surrounding the tumor and often involve the superficial skin and mucous membranes. The most important aspect of these changes is that they are temporary and will resolve with time. It is critical to keep your pet from traumatizing such areas and to maintain a clean and dry environment for these few weeks. In the mouth, such changes can cause soreness and result in decreased appetite. Soft, warmed food and prescribed medication will generally ensure comfort during this time. In the most extreme cases of anorexia, a feeding tube can be placed down the throat until the patient is eating well again.

"Late" side effects often occur in normal tissue surrounding the tumor that has a prolonged regenerative time, such as bone and nerve tissue. Effects in these areas are more challenging to manage successfully. For this reason, the method and dosing schedule of radiation is adjusted according to these tissues to avoid such problems. The initial treatment planning process will be critical to address such issues.

What diagnostic tests are performed prior to, during and after radiation therapy? How will we know if therapy is effective?

Prior to treatment, routine blood and urinalysis are recommended for comprehensive understanding of your pet’s overall health. X-rays, particularly chest x-rays, are used to ensure that no evidence of metastases (spread of the cancer) is present. A biopsy of the tumor is required prior to any treatment plan and additional biopsies, such as lymph node analysis are generally helpful. More specific tests, such as an MRI or CT scan, may be recommended to determine the exact extent of your pet's cancer.

During radiation therapy, other tests, such as blood tests, may be warranted to monitor your pet’s progress. After radiation therapy, a follow-up evaluation will be done with an oncologist. Subsequent evaluations may be done with your family veterinarian. The effectiveness of the radiation therapy can generally be determined by physical examination by a veterinarian. Other tests, such as x-rays, ultrasound, MRI, CAT scan or biopsy may also be helpful to determine tumor response.

We will try to discern the exact needs of your pet’s care during the initial treatment planning and estimate the costs of such tests prior to therapy. As always, we welcome your questions and concerns at any time during therapy.