PDT in Squamous Cell Carcinoma: Treatment of Inoperable Oral Tumor and Skin Cancer in Cats

Photodynamic therapy (PDT) is a treatment that uses drugs, called photosensitizer, along with light to kill cancer cells. The drugs only work after being activated by certain wavelengths of light. PDT is also called photo radiation therapy, phototherapy, or photo chemotherapy. It was first used to treat cancer over 100 years ago. Depending on the part of the body being treated, the photosensitizing agent is either injected into the bloodstream or put on the cancer surface. Over a certain amount of time the drug is absorbed by the cancer cells. Light is then applied to the area to activate the mTHPC. Light reacts with the drug, breaking it down and releasing a single oxygen atom. The oxygen destroys cancer cells and the blood vessels that feed them. It also alerts the immune system to attack the cancer. The drug-to-light interval is the period of time between when the drug is given and when the light is applied. It ranges from several hours to several days and depends on the drug used. Squamous cell carcinoma is the most common cancer found in cats and dogs. It is locally invasive but slow to metastasize. Its' development is often associated with poorly-pigmented skin and UV exposure. In pets the most common areas for SCC are the ear, the nose and the oral cavity.