Squamous cell carcinoma (SCC) is a fairly common tumor found in cats. There are 3 major types of squamous cell carcinoma in cats: Oral squamous cell carcinoma occurs in and around the mouth. It is the most common malignant oral tumor in cats. Solar-induced cutaneous squamous cell carcinoma is a cancer of the skin that occurs due to exposure to the sun. Bowen’s disease, also called Bowenoid carcinoma, or squamous cell carcinoma in situ, is a skin cancer that usually occurs in multiple sites but progresses very slowly. Since each of these types of squamous cell carcinoma have different characteristics and is treated differently, we will discuss each on separately. Oral squamous cell carcinoma in cats Oral squamous cell carcinoma in cats can occur in the mouth, on the lips, on or under the tongue, or in the tonsil area. Which cats are at risk for developing squamous cell carcinomas? Cats with oral squamous cell carcinomas are usually over 10 years of age. One risk factor for oral squamous cell carcinomas in cats is second hand smoke. Cats living in households with smokers appear to have an increased risk of developing oral squamous cell carcinoma. What are the symptoms of oral squamous cell carcinoma in cats? Cats with oral squamous cell carcinoma may have lesions in or around the mouth. The lesions often are ulcerated. Cats with this cancer may show a loss of appetite, weight loss, bad breath, drooling, or frequent chewing motions. How is oral squamous cell carcinoma diagnosed in cats? Diagnosis is usually confirmed by a biopsy. The biopsy can confirm the presence of a squamous cell carcinoma and also help stage the tumor (determine how invasive it may be). Radiographs (x-rays) are used to determine the extent of the problem. Computed tomography (CT) scans provide even more information. Lymph node biopsies may be performed to determine if the tumor has spread. How is oral squamous cell carcinoma treated in cats? Surgical removal of the tumor and the surrounding tissue is usually the treatment of choice. This can be difficult in the case of oral tumors that have become invasive. It often means a portion of the jaw must be removed. Surgery alone is seldom successful for oral tumors. Treatment may also include radiation therapy and chemotherapy. Supportive care including pain control and providing adequate nutrition is vital. Unfortunately, recurrence of the tumor is quite common. The prognosis is better if the tumor is identified very early and treatment is intensive. Solar-induced cutaneous squamous cell carcinoma in cats Solar induced squamous cell carcinoma of the skin typically involves the nose, ears, lips, and eyelids. It is common to find it in more than one site. Which cats are at risk for developing solar-induced cutaneous squamous cell carcinomas? Cats that spend time outdoors in the direct sunlight are at an increased risk of developing solar-induced squamous cell tumors. Cats with thin, light colored hair (especially white) on these areas are at the greatest risk. Blue-eyes white cats are the most susceptible. Cats are usually over 3 years of age when diagnosed with solar-induced cutaneous squamous cell carcinoma. What are the symptoms of solar-induced squamous cell carcinoma in cats? Squamous cell carcinoma of the skin usually occurs on the ears or bridge of the nose, eyelids, face, and sometimes the toes. The lesions may appear as ulcers with or without scabs, or as nodules with a rough surface, similar to a wart. These lesions are usually slow growing. How is solar-induced cutaneous squamous cell carcinoma diagnosed in cats? Biopsies are performed to obtain the diagnosis. In some cases, this cutaneous squamous cell carcinoma can spread to the lymph nodes, lungs, and even the bones. How is solar-induced squamous cell carcinoma treated in cats? Surgical removal of the tumor and the surrounding tissue is usually the treatment of choice. Radiation therapy or cryosurgery (“freezing” the tumor) may also be used. Sometimes chemotherapeutic drugs are injected directly into the lesion. Prevention of recurrence consists of limiting the time that susceptible animals spend out in the sun. When thin-coated or sensitive animals do spend time outdoors during the prime daylight hours, a waterproof SPF 15 or greater sun block should be used on the ears and nose area. Bowen’s disease in cats Bowen’s disease is uncommon in cats, and appears to be related to a suppressed immune system and infection with papillomavirus. Which cats are at risk for developing Bowen’s disease? Cats who are immunosuppressed and/or infected with papillomavirus appear to be at increased risk. What are the symptoms of Bowen’s disease in cats? Unlike solar-induced cutaneous squamous cell carcinoma in cats, Bowen’s disease usually occurs in pigmented areas of the body that do not receive direct sunlight. It commonly appears in multiple sites on the neck, body, and limbs. Lesions may come and go. Long-standing lesions can develop into invasive squamous cell carcinoma. How is Bowen’s disease diagnosed in cats? Biopsies are performed to obtain the diagnosis. How is Bowen’s disease in cats treated? Surgical removal of the tumor and the surrounding tissue is usually the treatment of choice. If there are a large number of lesions, they can be treated with imiquimod (Aldara), which is applied directly to the lesions. Early treatment is important, before the lesions can potentially become invasive.
Feline oral squamous cell carcinoma: An overview These fast-growing, painful tumors are not uncommon in cats, and few affected patients survive long-term. But a patient’s chances can improve if you identify and address the disease early. Jun 01, 2007 By Laura D. Garrett, DVM, DACVIM (oncology), Sandra Manfra Marretta, DVM, DACVS, DAVDC, Jennifer J. Marretta, DVM VETERINARY MEDICINE 12345678Next Figure 1. The typical appearance of a sublingual squamous cell carcinoma with an irregular and ulcerated proliferative mass. The oral cavity is a common site for neoplasia in cats, accounting for about 10% of all feline tumors.1 The most common malignant oral tumor in cats is squamous cell carcinoma.1 The prognosis for this fast-growing, invasive tumor is grave, so it is vital to identify and treat it early. To help you manage affected patients, this article focuses on the biologic behavior, pathology, etiology, diagnosis, staging, and treatment of feline oral squamous cell carcinoma. BIOLOGIC BEHAVIOR Figure 2. Note the ulceration and necrosis associated with this sublingual squamous cell carcinoma that eroded through the dorsal aspect of the tongue. Oral squamous cell carcinoma is a malignant tumor that may occur anywhere within the oral cavity, is locally invasive, infrequently metastasizes to ipsilateral regional lymph nodes, and rarely spreads to distant sites.1,2 The most common site of oral squamous cell carcinoma in cats is the sublingual region (Figure 1). The maxillary and mandibular gingivae are also sites of primary tumor development. Infrequently, squamous cell carcinoma may arise from the tonsillar epithelium. Figure 3. An intraoral view of a left mandibular squamous cell carcinoma demonstrating the widening of the mandible around the teeth without an obvious raised and proliferative mucosal lesion. Mucosal ulceration, necrosis, and severe suppurative inflammation are commonly associated with oral squamous cell carcinoma (Figure 2). Gross tumor proliferation is often evident in the oral cavity. However, the mucosa can also remain intact over a raised region caused by squamous cell carcinoma invading into deeper tissues (Figure 3). Cats may present for evaluation of an enlarged jaw, as the tumor can make the mandible look prominent or asymmetrical (Figure 4). Gingival squamous cell carcinoma often invades the underlying mandible or maxilla, leading to severe and extensive tumor involvement of the bone in that area. Local disease is usually the cause of death. PATHOLOGY Figure 4. The same cat as in Figure 3 showing rostral and left mandibular enlargement. Oral squamous cell carcinomas grow rapidly. On initial presentation, the tumor is often extremely advanced, resulting in a grave prognosis. The metastatic rate at diagnosis is low, yet the true metastatic potential is unclear because so few cats have their local disease controlled to permit long-term follow-up for metastatic disease.2 In four studies comprising 81 cats with oral squamous cell carcinoma, 12 cats (14.8%) had documented metastasis to the ipsilateral submandibular lymph node.3-6 The actual rate of metastasis may have been somewhat higher, as not all cases had cytologic or histologic lymph node evaluation. In eight cats (10%), metastasis was diagnosed at presentation,3-5 while four cats (5%) developed lymph node metastasis after primary tumor treatment.6 Of these four cats, one was euthanized because of the metastasis; the other three were euthanized because of local tumor progression.6 Thoracic radiographs were evaluated in three of the studies, comprising 74 cats, and no evidence of thoracic metastasis was present at initial presentation in any patient.3,5,6 In one cat that had lymph node metastasis, follow-up thoracic radiographs 16 months after treatment showed no evidence of pulmonary metastatic spread.4 These findings are consistent with the belief that feline maxillofacial squamous cell carcinomas have a low metastatic rate and that local disease is usually the cause of death. ETIOLOGY AND RISK FACTORS The average age of cats with oral squamous cell carcinoma is 12.5 years, with a range of 3 to 21 years. No significant sex or breed predilection is associated with this tumor. Although several environmental risk factors have been recognized, the cause of feline oral squamous cell carcinoma remains poorly defined. Various potential contributing factors are discussed below. Passive smoking One clinical study found that cats exposed to household environmental tobacco smoke appear to have an increased risk of developing oral squamous cell carcinoma.7 Cats that had ever lived in a household with a smoker had a nonstatistically significant twofold increase in risk of oral squamous cell carcinoma compared with cats in nonsmoking households. Cats whose owners reported smoking one to 19 cigarettes a day had a statistically significant fourfold increase in the risk of oral squamous cell carcinoma compared with cats in nonsmoking households.7 Another study of p53 expression in oral squamous cell carcinoma determined that cats exposed to any environmental tobacco smoke were four and a half times more likely to overexpress p53 in their tumors than were unexposed cats.8 The p53 protein, the product of a tumor suppressor gene, regulates cell growth and proliferation and prevents unrestrained cell division after chromosomal damage. Abnormal p53 accumulates in the cell, unlike normal, wild-type p53, and can be detected via immunohistochemistry. The absence of functional p53 increases the risk of developing various cancers, and it is suggested that p53 may be a possible site for carcinogen-related mutations within some squamous cell carcinomas.8 12345678Next