With technology borrowed from human medicine, the radiation oncology team at the Flint Animal Cancer Center recently treated its first pet patient using superficial radiation therapy.
The new radiation machine, originally acquired through a collaboration with the James L. Voss Teaching Hospital’s ophthalmology service to treat squamous cell carcinomas on the eyelids of horses, is used by dermatologists in human medicine to irradiate skin lesions, including basal cell and squamous cell carcinoma. The equipment is on loan from Sensus Healthcare to explore potential applications in veterinary medicine.
The patient, Daisy, was diagnosed with two small mast cell tumors, one on her muzzle and the other on her lower eyelid. One treatment option offered was surgery. However, to be sure surgeons completely removed the cancer, Daisy would likely lose her eye. Traditional radiation therapy was another option, but Flint Animal Cancer Center radiation oncologists determined that the tumors were too small for the large linear accelerator.
“Mast cell tumors typically respond quickly to radiation,” said Dr. Tiffany Martin, radiation oncologist. “With that knowledge, we believed superficial radiation therapy was a good choice to offer Daisy’s family.”
Daisy’s family agreed to try the new therapy.
Radiation oncology resident Dr. Alicja Reczynska worked with Martin and medical physicist Dr. Del Leary to develop Daisy’s treatment plan. Part of the strategy involved using a ceramic-coated tungsten shield to protect Daisy’s eye from any radiation exposure
“Even though this low energy beam only interacts near the surface of the body, the location of the tumor on the eyelid yielded the potential of unwanted radiation reaching the eye itself. Therefore the additional precaution to completely shielding the eye was taken,” said Leary.
The portable unit, which according to the team, required less setup than the linear accelerator, delivered the appropriate dose of radiation at the surface level, as intended. The process takes only a few minutes, requiring less time under anesthesia.
Daisy recently completed her six planned treatments.
“We saw a really nice reduction in the size of both masses,” said Martin. “The only notable side effect was hair loss in the treatment field.”
With this first case complete, the Radiation Oncology service found the superficial radiation therapy modality effective in treating surface and superficial tumors with negligible normal tissue damage. As an added benefit, the technology can be easily adapted to treatment conditions and tumor changes on treatment delivery.
“Looking forward, we will likely see increased use for this technology in other superficial skin or oral cancers and could potentially be used with interoperative surgery to treat questionable surgical margins,” said Martin.
For more information on superficial radiation therapy, please email the Flint Animal Cancer Center Radiation Oncology service.