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Veterinary Medicine

Deadly oral carcinoma target of new research project

March 1, 2010

Squamous cell carcinoma is the most common type of oral cancer diagnosed in cats. It also is one of most devastating diagnoses a cat's owner can hear. The most owners can hope for right now are treatments that enhance the quality of life for the remainder of the cat's life, which is a median of six months with oral squamous cell carcinoma. But a groundbreaking research project at Colorado State University may give new hope to veterinarians and cat owners.

Need for better understanding of tumors

Drs. LaRue and Yoshikawa with a furry friend.

“Oral squamous cell carcinoma is absolutely devastating in cats, and accounts for about 10 percent of all feline tumors diagnosed,” said Dr. Susan LaRue, a professor in the Department of Environmental and Radiological Health Sciences and principal investigator on the project.

“Veterinary medicine has tried absolutely everything to improve the health outcomes for cats with SCC, but to no avail. We need a better understanding of these tumors as well as new tools to treat them.”

Depending on the location of the tumor, cats with SCCs often have difficulty eating, drinking, and eventually breathing. By the time a tumor is diagnosed, it has often made its way into the surrounding bone. The visible part of the tumor is often just the tip of the iceberg.

Deadly disease

Secondary infection is common and cats typically begin to weaken as the disease progresses. When quality of life deteriorates, owners often have no choice but to euthanize their pets.

The Morris Animal Foundation has provided funding to Dr. LaRue and her colleagues to begin a three-year program of tumor study and treatment. One of the primary goals of the study is to try to understand the molecular properties of SCCs and why they are so difficult to treat.

“We will be looking at tumor oxygen levels to better understand response to radiation therapy and chemotherapy,” said Dr. Hiroto Yoshikawa, a graduate student working on the project. “If a tumor is hypoxic it doesn’t respond very well to either type of treatment.

Looking at how the tumors grow and evolve over time

We’ll also be looking at epidermal growth factor receptor expression, the levels of which relate to poor prognosis, and microvascular density, as well as mapping tumors to see which parts are hot and which parts are cold. These tumors can vary greatly from one part to another – they are not homogenous – so we want to develop  a greater understanding of how they grow and evolve over time.”

Part of the problem of treating SCCs, said Dr. LaRue, is that the biology of the tumors themselves is not well understood. This study hopes to better define the underlying biology of SCCs. In addition to evaluating the molecular tumor characteristics of SCCs, investigators will be treating cats with SCC using stereotactic radiation therapy.

Treating cats with stereotactic radiation therapy

Drs. LaRue and Yoshikawa exam an image showing a cat with an oral carcinoma.

In SRT, veterinarians can give higher doses of radiation over a shorter period of time with the hopes of improving tumor control and survival. SRT also has a lower risk of damage to surrounding tissue and other side effects. The study will enroll 10 cats each in the first and second years, with the third year devoted to evaluation and follow up.

“This type of treatment is already being used in human medicine with success, so in this case humans are being very nice guinea pigs for our feline patients,” said Dr. LaRue. “We want to be able to give cat owners a treatment option that can increase the length and quality of their cat’s life, something we are not able to do right now, so we are very excited about the possible outcomes of this study.”

Latest radiation, diagnostic imaging equipment make study possible

New radiation and diagnostic imaging equipment are making this study possible. Researchers will be using the Varian Trilogy Linear Accelerator to deliver radiation treatment, and also will use the new PET/CT scanner for imaging and treatment staging. Drs. LaRue and Yoshikawa are joined in this project by Dr. E.J. Ehrhart, who is responsible for histology; Joseph Charles, molecular pathology technician; and Kelly Carlsten, Animal Cancer Center clinical trials coordinator.

To participate in the study, cats must have a diagnosis of oral squamous cell carcinoma. Full details about clinical trial qualifications and enrollment are available at the Animal Cancer Center clinical trials website.

Originally published in the Winter 2010 ERHS Emitter.