Oral squamous cell carcinoma (SCC) arises from the cells lining the oral cavity, and is the most common oral tumor encountered in cats and humans. While oral SCC has the potential to both aggressively invade local tissue and spread to other parts of the body, it is often the local effects of the tumor that cause the most problems. We do not know what causes SCC to occur in cats. Diagnosis and Initial Evaluation Many cats with oral SCC will display signs such as drooling, foul odor, bleeding from the mouth, or difficulty eating. Some cats may present with signs suggesting a dental problem, and SCC is diagnosed as an underlying cause of the dental disease. A diagnosis of SCC usually requires a biopsy. This is sometimes performed during routine dentistry, or can be performed using quick-acting injectable sedation or a very short anesthetic. Prior to devising a treatment plan, some tests will often be performed to determine overall patient health, and if the tumor is localized to the primary site or whether there is any evidence of spread. These tests include blood tests evaluating blood cell number and organ function, a fine needle aspirate of the lymph node draining the tumor area, and X-rays of the lungs and/or tumor site. Treatment and Prognosis Whenever possible, surgery is the first line of defense for SCC. Unfortunately, due to the very small size of a cat’s mouth and the relatively large size of the tumor when it is usually diagnosed, surgery is possible in less than 10% of cases. When surgery can be performed, very aggressive surgery, often removing parts of the upper or lower jaw, is recommended because of this tumor’s ability to deeply invade bone and other deep structures in the mouth. In cases where surgery is not possible or has been declined, another form of local therapy, radiation therapy can sometimes be used. This involves the local application of a powerful form of radiation directly onto the tumor area. By itself, radiation therapy is rarely associated with significant tumor shrinkage. However, it has the potential to decrease pain associated with the tumor, and especially when combined with other forms of therapy, may increase the likelihood of meaningful tumor shrinkage occurring. Stereotactic radiation surgery involves higher doses of radiation given over 3 treatments. This is still considered a palliative treatment with only 40% of cats having a response and progression occurs in a few months. There are several chemotherapy drugs that have been studied for the treatment of SCC in cats. The likelihood of a patient experiencing meaningful tumor shrinkage with these drugs is typically less than 10%, however more cats may experience mild tumor shrinkage. There is a small molecule inhibitor called Palladia. This appears to have some effect against SCC in cats. Palladia is a pill given at home, and most cats tolerate it well but side effects can occur (see Palladia handout). Palladia would help to shrink the tumor to make them more comfortable. Cats on this therapy have been found to tolerate it well overall, and those taking Palladia lived longer than those not on therapy. With Palladia many cats succumb to the disease within a few months. Another form of treatment that has the potential to be useful in treating SCC is piroxicam which is sometimes effective in dogs with SCC. Piroxicam could make other treatments, like chemotherapy and radiotherapy, more effective. In addition to its potential antitumor effects, piroxicam is a very strong analgesic (pain medication), and can be helpful in addressing the discomfort and mouth irritation that can be associated with oral SCC. We do not recommend this medication in cats with kidney disease. Unfortunately, we are unable to cure cats with SCC. The goal with treatment is to do as much as we can to maintain an excellent quality of life for as long as possible. Sadly, regardless of the form of therapy chosen the survival is generally only a few months. Palliative care with pain medications and antibiotics are recommended to try to keep cats comfortable for as long as we can with this cancer.