cancer cures: dr. kim smyth explains radiation therapy
When pets are diagnosed with cancer, we first weigh the various treatment options. In general, the goal when cancer is present is to get rid of the cancer cells if possible. We can do that in one or more of the following ways:
We’ve discussed chemotherapy before in its own blog, and today we are going to address a more local therapy: radiation.
Both surgery and radiation are considered local therapies, as they address the cancer cells directly at the source (or locally). When we use the surgical option on a tumor, we attempt to cut it out. Cutting out the tumor is often preferred, because we can be sure that we removed the whole thing by sending samples to the lab for microscopic analysis. But surgery isn’t always practical; sometimes tumors are too large to remove surgically. Sometimes there are located in places that are not amenable to surgery. When these cases arise, we often turn to radiation therapy.
Radiation therapy uses high energy x-rays to damage the DNA of tumor cells, thereby killing them. Radiation can be used in combination with surgery and/or chemotherapy to try to achieve control of cancer or maybe even to cure it. When cancer is advanced or has spread to other parts of the body, radiation can be used to alleviate symptoms, improving quality of life.
Radiation can be used for many different types of tumors, including:
sarcomas, such as osteosarcomas (bone cancer) and vaccine associated sarcomas
bladder and prostate tumors
mast cell tumors
The radiation therapy schedule will vary depending on the desired effect of its use. When the goal is palliative care, pets may only need to have radiation therapy once or twice. On the other hand, pets who undergo radiation therapy in hopes of controlling their cancer will likely have 10 to 30 radiation treatments over three to six weeks.
Because we can’t simply ask our pets to lie still for their treatment, they will undergo light anesthesia prior to each treatment. The treatments are painless and last only a few minutes.
Radiation therapy is not new—it has been used in veterinary medicine since the early 1900s. However, modern radiation therapy is better at targeting cancer cells, increasing its effectiveness while decreasing adverse effects associated with its use. However, many pets will still experience some adverse effects from their radiation treatments. Normal skin that is exposed to the radiation beam may develop a sunburn-like rash. Treatment of oral tumors can cause uncomfortable mouth sores that may make it painful for affected pets to eat. And when a patient’s eye falls in the beam of radiation, cataracts or retinal disease may occur months to years down the road.
Side effects are generally easily managed, and are a small price to pay if radiation therapy adds many happy months or years to our pets’ lives. How fortunate we are to live in an age where radiation and chemotherapy are available for our pets!