Feline squamous cell carcinoma

Among the most common malignant cancers of cats, feline squamous cell carcinoma has a wide range of survival expectations and treatments. The neoplasm tends not to produce distant metastases, but is highly invasive, and, especially in the mouth cavity, can interfere with quality of life.

Early diagnosis is key. A biopsy is likely to be needed, possibly aspirational but preferably incisional.

Treatment

Detected very early, the tumor may be removable by surgery, but, in most cases, it is inoperable yet the surgery allows a definitive histopathological diagnosis.

Assuming the owner authorizes active treatment, the first steps are radiation or radiation coupled with chemotherapy, followed by additional cycles of chemotherapy and possibly additional radiation.

Radiation

Basic palliative radiotherapy uses fractionated radiotherapy, usually over four weeks. An accelerated protocol has been described and is being adjusted for the complete responders.

Antineoplastic agents

Bleomycin and carboplatin are the most common adjuvant and palliative antineoplastic agents. As with any cancer chemotherapy, the challenge is managing the toxicity. Weekly complete blood counts are a standard of care, as, of course, the owner's observations about the cat's activity and moods.

Bleomycin is given as a weekly subcutaneous injection, for up to 16 weeks. After 16 treatments, there is a high risk of pulmonary fibrosis. It is less myelosuppressive than carboplatin.

Carboplatin is administered intravenously every 3 to 4 weeks. Its use is off-label and the dose is still being optimized. In general, a new treatment is not started until the Combined chemotherapy has been explored in early trials, and, while theoretically promising, is not yet within the standard of care.

Role of NSAIDs

Some of the tumors express cyclooxygenase-2, so a selective NSAID, such as meloxicam, offers both pain relief and the potential to reduce the inflammation of a tumor. Unfortunately, these agents also can cause life-threatening gastrointestinal bleeding.Misoprostol has not been useful as a prophylactic drug, as its overall effects on prostaglandins cause severe side effects. It is not standard practice to administer them with a prophylactic proton pump inhibitor or histamine H2 antagonist.

Experimental treatments

There is substantial research in protocols using specialized radiotherapy, (e.g., plesiotherapy) which have substantially extended life. Various studies have used electric stimulation, hyperthermia and hyperbaric oxygen as a supplement to chemotherapy or radiotherapy. Photosensitization and photodynamic therapy is being explored.

Quality of life

The tumor itself may not be painful; the concern, especially in oral cancers, is that it interferes with eating or breathing.

The cat may suffer pain after manipulation of the tumor for examinations or oral medication, or perhaps by trauma (e.g., while eating). Pain management is a challenge in cats, due to their intolerance of many opioid analgesics. Gabapentin can provide baseline pain relief. Buprenorphine, orally, in the buccal cavity, or subcutaneously is useful for breakthrough pain.

Complications

Especially when radiation or carboplatin are in use, the patient's defenses to infection are reduced. The tumor itself can predispose to infection.