Squamous Cell Carcinoma in Cats
Key takeaways
Squamous cell carcinoma (SCC) is a cancer of the flat cells that line many tissues in cats, such as the skin, mouth, and esophagus.
- SCC occurs most commonly where hair is sparse or light-colored as there is less protection from UV rays
- Typically, SCC is found on the ears, nose, lips, inside the mouth, and at the nail beds
- The characteristic symptom is a small, rough sore on the surface of the skin or membrane
- Immediate veterinary attention is required since early detection is crucial to good outcomes
- Diagnosis requires biopsy
- If the tumor is caught in the early stages, treatments include radiation, chemotherapy, and surgical excision
- Later stages usually impact quality of life, resulting in euthanasia
- Prevention is possible by reducing sun exposure and maintaining regular dental and veterinary health checks
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A closer look: Squamous Cell Carcinoma in Cats
Developing cancer is uncommon in cats, with squamous cell carcinoma being the second most common cancer in this species.
Common locations for squamous cell carcinomas include the skin, mouth, and nasal sinuses. In some cases, SCCs can develop in the lungs.
The severity of SCC depends on how far the cancer has progressed before it is treated. Early stages are characterized by discrete, individual tumors that have not grown deeply and have not spread to other tissues. Later stages are characterized by deep invasion into the skin or mucous membrane, spreading to other tissues and metastasizing to other structures in the body.
In cases where SCC is detected early, treatment is straightforward and often curative. Left untreated, squamous cell carcinoma progresses, often spreading to other organs in the body. Once this has occurred, treatment is more complex and prognosis is poor.
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Risk factors
Cats with light-colored or patchy fur, particularly those who spend a lot of time outside or in sunlight, and cats with underlying conditions like papillomavirus, are most at risk. Older cats are more susceptible than young ones.
In rare cases, two or more skin tumors occur in different locations on the body at the same time. This is called multicentric SCC, Bowen’s disease, or Bowenoid carcinoma.
Cats who chew, bite, lick or scratch at affected areas are at risk of causing injury and infection.
Possible causes
Squamous cell carcinoma is a cancer of the flattened cells that line external organ structures such as the skin, mouth, and esophagus. SCC develops when the DNA of the cells is damaged, causing cells to proliferate and form a tumor.
Many cases of SCC are related to exposure to ultraviolet light. UV radiation is directly damaging to DNA. These tumors are most commonly seen on the tips of the ears, the nose, and the lips.
Cases of oral SCC are often related to chronic inflammation or dental disease.
Cases of SCC at the nail beds are often offshoots of lung cancer. The connection between the toes and the lungs is known as the lung-digit syndrome.
Main symptoms
Most squamous cell carcinomas in cats noticed at home are found on the skin or nail beds. The symptoms of early-stage SCC of the skin are small sores.
Oral SCC symptoms can sometimes be mistaken for dental disease or other diseases of the mouth.
In cats, cancers of the lung commonly metastasize to the digits (also called lung-digit syndrome). Upon metastasis, lameness may also be an associated symptom of lung SCC.
Testing and diagnosis
Cats with small, scabby bumps on their ear tips, nose, lips, or toes, as well as cats with lesions in their mouths, require immediate veterinary care.
Diagnostic tools include:
- Physical examination
- Fine needle aspiration
- Biopsy
- X-rays and ultrasounds
If the diagnosis is SCC, it is often recommended to determine which stage the cancer is in.
Staging tools include:
- Blood work
- Urinalysis
- X-ray and ultrasound
Steps to Recovery
Referral to a veterinary oncologist is possible to determine the most effective treatment routes.
Early stage SCC is treated with:
- Cryosurgery (freezing the tumor)
- Surgical excision
- Radiation
- Chemotherapy
- Pain medications
- Antibiotics if secondary infections develop
Late stages of SCC are more complex. Additional treatments include:
- Debulking (removing part of the tumor to help preserve function of the underlying structure)
- Amputation of the affected area, in the case of SCC of the nail bed or of part of the nose
- Immune-response modifiers
Treatment of late stage SCC aims to slow the cancer’s progression and improve quality of life. Since it is not curative, euthanasia is sometimes the best option for these cases.
SCC is a progressive disease. If it is detected early and treated appropriately, prognosis is good.
In cases where the cancer is not detected until later stages, especially where metastasis has occurred, the prognosis is poor.
Prevention
Limiting UV exposure by keeping cats indoors during daylight hours and by using UV protectant shades on windows where cats spend their time is recommended.
Routine veterinary check ups are helpful to detect SCC early. Routine dental check-ups conducted annually are equally important, particularly in senior cats.
Is Squamous Cell Carcinoma in Cats common?
Squamous cell carcinoma is the second most common type of cancer in cats.
Typical Treatment
- Surgery
- Radiation
- Chemotherapy
