Feline Nasal Tumors
Nasal tumors are relatively uncommon in veterinary medicine accounting for less than 1% of all feline tumors. Middle to older aged cats are most commonly diagnosed with nasal cancer. To date, no specific breed or sex predisposition has been noted. The most common types of nasal tumor are either a carcinoma or lymphoma, which are equally split (50/50) of all nasal tumors. Other tumors include squamous cell carcinoma, undifferentiated carcinoma, and sarcomas (chondrosarcoma, osteosarcoma, and fibrosarcoma). Most of these tumors are locally invasive and cause a great deal of destruction within the nasal cavity but <25% will spread to the lungs or local lymph nodes.
The most common presenting complaints for cats with this cancer include nasal discharge, nasal bleeding (epistaxis), facial deformity (swelling), sneezing, abnormal breathing sounds due to airway obstruction, ocular abnormalities, anorexia, lethargy, weight loss and difficulty chewing. The diagnosis of nasal tumors includes bloodwork (CBC and serum chemistry, FeLV/FIV testing), chest radiographs, nasal radiographs or CT scan of the nasal cavity, oral exam, lymph node aspirates and biopsies (may require rhinoscopy). Definitive diagnosis is based upon biopsy, nasal flushing or trucut/surgical biopsy. Results of these diagnostics (Computed tomography, chest radiographs, Lymph node aspirates) also help with staging of the patient, which means looking to see where else the cancer may be. The CT is also very important in the planning for radiation therapy,
Treatment for this cancer generally involves radiation therapy +/- chemotherapy. Surgery is not a primary form of therapy due to the extent of most of these tumors make a complete excision very difficult. This is also not an uncomplicated surgery and often involves weeks of recovery and in most cases, the tumor is not completely removed with surgery. Radiation therapy typically involves giving “full course” therapy in which cats receive 15-20 daily treatments, although there are alternative protocols. With this protocol, acute side effects include inflammation of the mouth and nose (mucositis, glossitis), which begin two weeks into therapy and end two weeks after completion of therapy. These are often managed supportively with anti-inflammatory medications, pain medication, and antibiotics. Eye abnormalities may occur depending upon where the tumor is located in relation to the eye. The overall survival times with this protocol range from 50% of the cats living 1 year or longer.
In cases where the tumor is considered on histopathology to be very aggressive and thus have a greater chance to spread, chemotherapy will be added to the protocol either during radiation therapy or after. In this scenario, chemotherapy is given at a systemic dose designed to kill any cancer within the nose or elsewhere. In some cases, where radiation therapy is not possible, chemotherapy can be used as a sole therapy, however, chemotherapy alone has not been shown to consistently prolong survival. Lastly, drugs in the class called NSAIDs have been shown to work against these tumors by directly killing them, destroying blood vessels feeding tumors, altering the immune systems to attack cancer and to increase the sensitivity of cancer to radiation therapy and chemotherapy. In cats, Feldene or Meloxicam may be used. These drugs are given orally throughout the protocol and indefinitely thereafter. Being like aspirin, these drugs can be irritating to the stomach and damage the kidneys. Therefore, bloodwork is performed prior to starting them and periodically thereafter. If any animal develops kidney value abnormalities the drug is discontinued and it is not used in patients with pre-existing renal problems.
Although achieving a cure for this cancer is very difficult, with therapy many cats maintain an excellent quality of life and can have an increase in survival.