Lung Cancer (Squamous Cell Carcinoma) in Cats

Since cat owners cannot view an internal lung tumor, clinical signs of coughing, difficulty swallowing and weight loss are the only indications that something is wrong. The prognosis for lung cancer in cats is guarded to poor, but as with all forms of cancer, a more positive outcome can be expected with early detection. 

Lung cancer in cats caused by squamous cell carcinoma growth is a type of malignant cancer found in the lungs and lower respiratory system of felines. Squamous cell carcinoma tumors are ulcerations that grow in a cauliflower-like formation. The masses are raised and usually have a reddish color, which can only be seen with a bronchoscope. A bronchoscope is a flexible scope that allows the veterinarian the view the lungs and airways in a procedure known as a bronchoscopy. 

Common clinical signs associated with lung cancer include: 

• Coughing 
• Difficulty breathing 
• Difficulty swallowing 
• Excessive saliva production 
• Exercise intolerance 
• Weight loss 
• Overall weakness
• Tiredness 

Squamous cell carcinoma lung cancer in cats is believed to be primarily caused by exposure to environmental carcinogens, such as tobacco smoke. However, experts also believe that use of flea collars could also be a possible link to this cancerous condition. Although this disease can affect cats of all ages, most felines diagnosed with squamous cell carcinoma lung cancer are middle-aged or older. Veterinarians also tend to see squamous cell carcinoma masses in more light pigmented or white cats more than those with darker colored skin. As sun exposure seems to be a common cause of skin squamous cell carcinomas, it is to be assumed that sun exposure can also play a part in lung tumors of squamous cell nature. 

As a cancerous growth in the lungs cannot be readily viewed, the first stages of the diagnostic process will begin with talking to the veterinarian about your cat’s current symptoms. Telling the vet the main reason you brought your cat into the clinic will be extremely helpful in the diagnosis, as the abnormality that was of concern to you will also be a concern for the veterinarian. Be prepared to answer the following questions upon arrival:

• Why did you bring your cat in to see the veterinarian? What is your main concern? 
• What symptoms has your cat been displaying?
• How long have the symptoms been going on? 

The veterinarian will then review the feline’s medical record to ensure he or she is up-to-date on all current vaccinations, as common feline viruses can also affect the respiratory system. The feline doctor will then move onto a physical exam that may provide limited information, therefore, the following routine diagnostic tests will likely follow the physical exam: 

• CBC (complete  blood cell count)
• Biochemistry blood profile 
• Urinalysis 
• Chest ultrasound 
• Radiograph of the chest 
• CT scan 
• Bronchoscopy: A procedure performed using a bronchoscope to allow the veterinarian the view the lungs and airways. 
• Fine needle aspiration
• Biopsy 

The only way to truly diagnose lung cancer and more specifically, squamous cell carcinoma of the lungs, is through a cytology. A cytology is the examination of cells to determine their nature. Therefore, a biopsy of the mass must be taken, removing a small section of tissue for this exam. 

The specific treatment the veterinarian recommends depends on the individual feline. The cat doctor will factor in the tumor location, invasive nature and the overall health of the feline. If possible, surgical removal of the tumor is the standard treatment choice for squamous cell carcinoma cancer in felines. If the tumor is very large or has invaded surrounding tissues, the veterinarian may suggest other treatment modalities such as: 

• Photodynamic therapy: the promotion of cell death by exposure to light, therefore, sensitizing the tumor. 
• Chemotherapy
• Radiation therapy: the use of a radiation beam directing energy towards the tumor

The prognosis for most cases of squamous cell carcinoma lung cancer in cats is generally poor. The outcome of this disease depends on evidence of metastasis, the degree of invasive nature, the size and location of the tumor. Your cat’s end prognosis will also depend on whether or not the tumor was completely removed during surgery. Like with all forms of cancer, early detection is key to a positive outcome.