What are the symptoms of oral squamous cell carcinoma (SCC) in cats?
Squamous cell carcinoma accounts for approximately 75% of all oral tumors in cats. The tumors are usually found on the
tongue, pharynx, tonsils, or jaws, and usually invade the surrounding bone. Although metastasis (spread) to other organs
is relatively rare, these tumors are locally aggressive and difficult to control. Most commonly observed symptoms of feline
oral SCC include drooling, bad breath, bloody discharge from the mouth, difficulty eating or loss of teeth. Tumors located
in the back of the throat can be particularly painful and will prevent swallowing.

How is oral squamous cell carcinoma diagnosed in cats?
A thorough diagnostic evaluation of oral tumors is critical due to the variety of different oral tumors that exist. Sedation or
anesthesia is often required in order to examine the pet's mouth, especially if the suspected tumors are located in the back
of the mouth or on the tongue. If the tumor is suspected to be malignant, chest X-ray can be done prior to
biopsy to check
for metastasis (spread) to the lungs.
Advanced imaging such as CT (computed tomography) or MRI (magnetic resonance
imaging) can be valuable tools in staging the disease (determining how advanced it is), especially for evaluating bone
invasion and tumor's potential extension into the nasal cavity, pharynx or the eye. The use of CT may eliminate the need
for regular X-rays but CT/MRI imaging is more expensive.

To check if any cancer cells have escaped from the mouth to the lymph nodes, lymph node aspirates (isolation of cells for
microscopic analysis) can be performed. The final diagnostic step, which is done under short anesthesia, is a large
biopsy. Biopsy is preferred over cytology or aspirates to definitively differentiate between benign (noncancerous)
and malignant (cancerous) tumors and determine the exact type of tumor present. This is important in order to plan
appropriate treatment that will best maximize the cat's response to therapy and survival. Routine bloodwork is usually
recommended to make sure the cat is in good overall health otherwise prior to anesthesia and biopsy.

What are the treatment options for oral squamous cell carcinoma in cats?
Surgical removal of the tumor is the fastest and most likely curative option for localized tumors that have not yet spread to
other organs. Therefore, surgery is usually the first treatment option whenever possible. Because these tumors are very
aggressive and invade deeply into the bone and other structures in the mouth, it is usually recommended to perform an
aggressive surgery, which may affect the cosmetic and functional appearance of the cat. Unfortunately, the small size of a
cat's mouth and the size of the tumor makes surgery possible in less than 10% of cats with oral SCC. For these cats, other
options exist such as radiation therapy or chemotherapy but only achieve little (and short-lived) success as described

Radiation therapy
Radiation therapy is a type of treatment that uses penetrating beams of high energy waves (gamma rays) or streams of
particles (generated by linear accelerators) that kill cancer cells by damaging their DNA.  Radiation therapy alone intended
for palliative reasons (aiming at providing relief) rather than curative reasons is not typically recommended for cats with
oral SCC due to the expected poor tumor control and risk of adverse effects. The side effects of radiation therapy can
include hair loss, inflammation of the oral cavity, difficulty swallowing, or eye changes. To learn more about this treatment,
please visit the
Radiation Therapy section.

The use of radiosensitizers (drugs that make cancer cells more sensitive to radiation) is a new way to try to improve the
cat's response to radiation therapy. In a study of eight cats that were treated with combination of gemcitabine (a
chemotherapy drug) and palliative radiation, two cats achieved complete response, four cats achieved partial response
and two cats had no response. In these cats, median survival time was 111.5 days (ranging from 11 to 234 days) and
median duration of remission was 42.5 days (ranging from 11 to 85 days) (Jones,
J Am Anim Hosp Assoc, 2003). In
another study with nine cats, using a radiosensitizer called etanidazole resulted in partial responses in all nine cats and
median survival was 116 days.

There is no known effective chemotherapy drug to treat oral SCC in cats.  Several chemotherapy drugs have been
evaluated in cats with oral SCC but in most cases, they only 'buy' some time rather than producing durable and meaningful

What is the prognosis for cats with oral squamous cell carcinoma?
Oral SCC is a very aggressive disease and there is no known effective treatment. Unfortunately, only very few cats get
cured and less than 10% of cats are alive after one year (even with combinations of radiation and chemotherapy). The
quality of life for the cats rapidly deteriorates and most cats are euthanized due to their inability to eat and drink within
three months of diagnosis.

Does cancer cause pain in cats?
Pain is common in pets with cancer, with some tumors causing more pain than others. In addition to pain caused by the
actual tumors, pets will also experience pain associated with cancer treatments such as surgery, radiation therapy or
chemotherapy. Untreated pain decreases the pet's quality of life, and prolongs recovery from the illness, treatment or
injury. It is, therefore, essential that veterinary teams taking care of pets with cancer should also play a vital role in
educating pet owners about recognizing and managing pain in their pets.

The best way to manage cancer pain in pets is to prevent it, a term referred to as preemptive pain management. This
strategy anticipates pain ahead of time and administers pain medication before the pet actually experiences pain, thus
ensuring the pet's maximum comfort. To learn more about how to recognize pain in pets with cancer and what cancer pain
management options are available for your pet, please visit the
Cancer Pain Management section.

How important is nutrition for cats with cancer?
Cancer cachexia (a term referring to progressive severe weight loss) is frequently observed in pets with cancer. Pets with
cancer lose weight partly because of lack of appetite and partly because of cancer-induced altered metabolism. Some of
the causes for decreased appetite are related to the cancer itself (for example, the tumors may physically interfere with
food chewing and swallowing) and some may be related to the side effects of cancer treatment (for example, some
chemotherapy drugs cause nausea and vomiting, and radiation therapy can cause mouth inflammation).

Proper nutrition while undergoing cancer treatment is essential to maintain your pet's strength, improve survival times,
quality of life and maximize response to therapy. Adequate nutritional support was shown to decrease the duration of
hospitalization, reduce post-surgery complications and enhance the healing process. Additionally, pets with cancer need to
be fed diets specifically designed to provide maximum benefit and nutritional support for the patient. To learn more, please
visit the
Cancer Nutrition section.

How do I find a qualified veterinary oncologist?
To locate a qualified veterinary oncologist worldwide in your area who can discuss with you appropriate cancer treatment
plan for your pet's cancer condition, please visit the "
Locate a veterinary oncologist" section.  

Are there any clinical trials investigating new treatments for oral squamous carcinoma in cats?
There are currently two clinical trials for for cats with oral squamous cell carcinoma. The first study is conducted by
Colorado State University and the second by University of Pennsylvania Veterinary Hospital. To learn more about these
trials (which are partially funded by the institutions), please visit
Oral SCC Clinical Trials for Cats.

Additionally, there are several clinical trials available for cats with any tumor type for which your cat may qualify. To learn
more these trials (which are partially or fully funded by the institutions), please visit the
Cat Clinical Trials (any tumor type)

To learn more about veterinary clinical trials in general, please visit the
Pet Clinical Trials section.

Additional online sources:

  • Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007.
  • Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins, 1998
  • Feline Oral Squamous Cell Carcinoma by Dr. Betsy Hershey, DVM, DACVIM (Oncology)
Oral Squamous Cell Carcinoma in Cats
Comprehensive guide to cancer diagnosis and treatment in cats and dogs
© 2007 Pet Cancer Center. ALL RIGHTS RESERVED.
Last updated 2/19/2017
Oral Squamous Cell