Squamous cell carcinoma (SCC) is the most common oral tumor in cats and typically affects middle-aged to older cats. Factors that may increase the risk of oral SCC include flea collars, high volumes of canned food, and household smoke exposure; however, there is no one factor that is known to cause SCC. Unfortunately, oral SCC is an aggressive locally invasive tumor that is difficult to control; it appears to have a low rate of spread to other sites (metastasis) but this may be simply due to the short survival times following diagnosis.
Signs & Symptoms
Oral SCC in cats are typically large, invasive and often ulcerated tumors that occur anywhere in the mouth, including under the tongue, the palate (roof of the mouth), the upper jaw (maxilla) and lower jaw (mandible). SCC often invades bone and thus can be associated with significant discomfort. Most cats see their veterinarian following identification of a mass or swelling by the owner, but other symptoms can include loose teeth, pain associated with the face or chewing, excessive drooling and often blood-tinged drool, lack of grooming, decreased appetite and weight loss.
Diagnosis of oral SCC requires a biopsy of the tumor with the cat under general anesthesia so that a good sample of the tumor can be collected. A thorough oral examination can be performed at the same time, and the tumor is typically measured and documented along with the location. While not diagnostic for SCC, the diagnostic work-up includes complete blood count and serum chemistry profile, lymph node assessment via cytology, and chest x-rays in order to confirm that the tumor SCC is confined to the mouth. For some tumors, particularly those located in the front of the lower jaw (mandible), advanced imaging with computed tomography (a CT scan) may be recommended.
Treatment & Aftercare
Unfortunately, there is no known effective treatment for oral SCC in cats that offers long-term control and survival. If possible, surgery is often the treatment of choice for small tumors, particularly those located in the front of the lower jaw. Most cats present with large (> 2 cm) tumors that are difficult to remove completely with surgery; post-surgery radiation therapy may be recommended in some cases or palliative radiation therapy may be offered in lieu of surgery. Chemotherapy likely does not play a pivotal role in management but may be palliative in some cases. Non-steroidal anti-inflammatory drugs can be useful in managing discomfort.
The prognosis for cats with oral SCC is poor and most cats will have survival times ranging from 3-6 months. Cats with small tumors located on the lower jaw (mandible) that are treated with surgery have a better chance of surviving for one year; however, most will still eventually succumb to the disease.
Jessica Lawrence, DVM, DACVIM (Oncology), DACVR (Radiation Oncology), MRCVS, DECVDI (Radiation Oncology)