Feline oral squamous cell carcinoma: An overview - Veterinary Medicine
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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.


VETERINARY MEDICINE


TREATMENT

Feline oral squamous cell carcinoma is an extremely locally invasive, malignant tumor. To date, no therapies or combinations of therapy have shown great success in treating this tumor. Local and regional disease control is the treatment goal. Surgery, radiation therapy, or radiation therapy combined with chemotherapy are the principal treatment modalities used. These treatment options have been widely unsuccessful because of failure of local control. The one-year survival rate is generally less than 10%, with a median survival time of about three months for most therapies.2 A concise and accurate summary of the prognosis for a cat with oral squamous cell carcinoma is not feasible. The literature describing this tumor type consists of mostly small studies involving cats with squamous cell carcinomas of various locations within the oral cavity and a wide range of treatments within those small populations. The following sections summarize the literature addressing therapy for this tumor in cats. Assessing an individual patient's tumor stage and location is critical in advising an owner regarding possible treatment options and likely outcome.

Surgery

Surgical excision of oral squamous cell carcinoma alone yields high recurrence rates. In eight cats treated with mandibulectomy alone, the median survival time was five and a half months (range five weeks to 12 months); only two of the cats were alive and free of disease at 10 and 12 months.16-18 In one study of 42 cats treated with mandibulectomy for oral neoplasia, 21 of the cats had squamous cell carcinoma, and their median survival time was 217 days, which was significantly shorter than cats with fibrosarcoma or osteosarcoma, whose median survival time was not reached (most of the cats were still alive at the time of calculation).6 One encouraging finding was that survival rates one year after mandibulectomy (43%) were the same as those at two years, implying that cats that lived one year had a good chance for long-term survival. Thirty-eight percent of the cats with squamous cell carcinoma developed local recurrences. For cats that did not have recurrence, the median follow-up time was 169 days; it is possible that more cats would have shown recurrence if their follow-up time had been longer. The high recurrence rate implies that the extent of disease was underestimated at the time of surgery or that it was impossible to obtain adequate clean margins with mandibulectomy.

Ninety-eight percent of the 40 cats that underwent mandibulectomy and survived perioperatively experienced acute morbidity such as dysphagia or inappetence, ptyalism, mandibular drift, and difficulty grooming in the first four weeks after surgery.6 Seventy-six percent of all the cats experienced one or more of these adverse effects for the remainder of their lives. Nevertheless, 83% of owners were pleased with their cats' quality of life and said they would choose this procedure again.6 Thus, mandibulectomy seems to be a reasonable choice for cats with mandibular squamous cell carcinoma, but owners need to be aware of the associated high morbidity.


Figures 8A-8C. Immediate (8A & 8B) and four-month postoperative (8C) photographs of a cat that underwent right hemimandibulectomy to remove a squamous cell carcinoma. Note the slight mandibular shift to the right (8B). (Photographs courtesy of Dr. Christine Warzee.)
Careful case selection and thorough surgical planning including advanced preoperative imaging may be needed to help ensure complete excision of these tumors. For the best outcome, tumors must be small at diagnosis and located rostrally in the mouth. Cosmesis can be quite good when mandibulectomy is performed by an experienced surgeon (Figures 8A-8C). Postsurgical care must be discussed with the owners. Aggressive surgical treatment may lead to mandibular drift and malocclusion, resulting in the cat's being unable to eat or drink temporarily or permanently. In these cases, supportive care, including a feeding tube, must be implemented. Mandibular drift may lead to the remaining lower canine tooth causing trauma to the hard palate during occlusion. Filing down the damaging tooth, possibly with a root canal procedure, is indicated in these situations.

Surgery is rarely curative when the tumor is located in the caudal region of the oral cavity or when the tumor crosses the caudal midline of the oral cavity.5 In these circumstances, less aggressive palliative surgery for cytoreduction before other therapies such as radiation or chemotherapy may be considered.


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Source: VETERINARY MEDICINE,
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