Feline squamous cell carcinoma: Difference between revisions
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Among the most common malignant cancers of cats, and the most common oral cancer, '''feline squamous cell carcinoma (SCC)''' has a wide range of survival expectations and treatments. The [[neoplasm]] tends not to produce distant metastases, but is highly invasive, and, especially in the mouth cavity, can interfere with quality of life. | Among the most common malignant cancers of cats, and the most common oral cancer, '''feline squamous cell carcinoma (SCC)''' has a wide range of survival expectations and treatments. The [[neoplasm]] tends not to produce distant metastases, but is highly invasive, and, especially in the mouth cavity, can interfere with quality of life. | ||
Early diagnosis is key. A biopsy is necessary. If there is a clinical suspicion during the surgical biopsy that SCC is likely, it can be extremely useful to get a [[ | Early diagnosis is key. A biopsy is necessary. If there is a clinical suspicion during the surgical biopsy that SCC is likely, it can be extremely useful to get a [[X-ray computed tomography|CT scan]] while under the same anesthesia. This is likely to be needed for radiation treatment planning, but having CT images from the same time as the biopsy is not simply "documenting the lesion", but is useful in other aspects of continuing treatment. | ||
==Etiology== | ==Etiology== | ||
Canned food (RR = 3.6; P =.014), and independently specifically tuna intake (RR = 4.7; P =.004), as well as exposure to flea collars (RR = 5.3; P =.002) increased the risk of SCC, but without [[P53]] overexpression. This study found environmental tobacco smoke to be a lower risk factor (P = .11). <ref>{{citation | Canned food (RR = 3.6; P =.014), and independently specifically tuna intake (RR = 4.7; P =.004), as well as exposure to flea collars (RR = 5.3; P =.002) increased the risk of SCC, but without [[P53]] overexpression. This study found environmental tobacco smoke to be a lower risk factor (P = .11). <ref>{{citation | ||
Revision as of 18:17, 26 June 2010
Among the most common malignant cancers of cats, and the most common oral cancer, feline squamous cell carcinoma (SCC) has a wide range of survival expectations and treatments. The neoplasm tends not to produce distant metastases, but is highly invasive, and, especially in the mouth cavity, can interfere with quality of life.
Early diagnosis is key. A biopsy is necessary. If there is a clinical suspicion during the surgical biopsy that SCC is likely, it can be extremely useful to get a CT scan while under the same anesthesia. This is likely to be needed for radiation treatment planning, but having CT images from the same time as the biopsy is not simply "documenting the lesion", but is useful in other aspects of continuing treatment.
Etiology
Canned food (RR = 3.6; P =.014), and independently specifically tuna intake (RR = 4.7; P =.004), as well as exposure to flea collars (RR = 5.3; P =.002) increased the risk of SCC, but without P53 overexpression. This study found environmental tobacco smoke to be a lower risk factor (P = .11). [1] P53 gene overexpression has been reported in cats exposed to environmental tobacco smoke. [2]
Treatment
Detected very early, the tumor may be removable by surgery, but, in most cases, it is inoperable yet the surgery allows a definitive histopathological diagnosis.
Assuming the owner authorizes active treatment, the first steps are radiation or radiation coupled with chemotherapy, followed by additional cycles of chemotherapy and possibly additional radiation. The owner's decision can be difficult; some cats will not respond at all to what may be quite expensive therapy, but others may have significant life extension with good quality of life.
Radiation
Basic palliative radiotherapy uses fractionated radiotherapy, usually over four weeks. An accelerated protocol has been described and is being adjusted for the complete responders. [3]
Antineoplastic agents
Bleomycin and carboplatin are the most common adjuvant and palliative antineoplastic agents. As with any cancer chemotherapy, the challenge is managing the toxicity. Weekly complete blood counts are a standard of care, as, of course, the owner's observations about the cat's activity and moods.
Bleomycin is given as a weekly subcutaneous injection, for up to 16 weeks. After 16 treatments, there is a high risk of pulmonary fibrosis. It is less myelosuppressive than carboplatin.
Carboplatin is administered intravenously every 3 to 4 weeks. Its use is off-label and the dose is still being optimized. [4] In general, a new treatment is not started until the Combined chemotherapy has been explored in early trials, and, while theoretically promising, is not yet within the standard of care. [5]
Role of NSAIDs
Some of the tumors express cyclooxygenase-2, so a selective NSAID, such as meloxicam, offers both pain relief and the potential to reduce the inflammation of a tumor. Unfortunately, these agents also can cause life-threatening gastrointestinal bleeding. Misoprostol has not been useful as a prophylactic drug, as its overall effects on prostaglandins cause severe side effects. It is not standard practice to administer them with a prophylactic proton pump inhibitor or histamine H2 antagonist.
Experimental treatments
There is substantial research in protocols using specialized radiotherapy, (e.g., plesiotherapy) which have substantially extended life. [6] Various studies have used electric stimulation, hyperthermia and hyperbaric oxygen as a supplement to chemotherapy or radiotherapy.[7] Photosensitization and photodynamic therapy is being explored.
Quality of life
The tumor itself may not be painful; the concern, especially in oral cancers, is that it interferes with eating or breathing.
The cat may suffer pain after manipulation of the tumor for examinations or oral medication, or perhaps by trauma (e.g., while eating). Pain management is a challenge in cats, due to their intolerance of many opioid analgesics. Gabapentin can provide baseline pain relief. Buprenorphine, orally, in the buccal cavity, or subcutaneously is useful for breakthrough pain.
Complications
Especially when radiation or carboplatin are in use, the patient's defenses to infection are reduced. The tumor itself can predispose to infection.
References
- ↑ Bertone ER, Snyder LA, Moore AS (2003), "(abstract) Environmental and lifestyle risk factors for oral squamous cell carcinoma in domestic cats", J Vet Intern Med 17 (4): 557-562
- ↑ L. A. Snyder, E. R. Bertone, R. M. Jakowski, M. S. Dooner. J. Jennings-Ritchie, A. S. Moore, "p53 Expression and Environmental Tobacco Smoke Exposure in Feline Oral Squamous Cell Carcinoma", Veterinary Pathology 41 (3): 209-214, DOI:10.1354/vp.41-3-209
- ↑ JL Fidel, RK Sellon, RK Houston, BA Wheeler (23 August 2007), "(Abstract) A Nine-Day Accelerated Radiation Protocol for Feline Squamous Cell Carcinoma", Veterinary Radiology & Ultrasound 48 (5): 482-485
- ↑ Kisseberth WC, Vail DM, Yaissle J, Jeglum KA, Couto CG, Ward H, Khanna C, Obradovich JE (2008), "(Abstract) Phase I clinical evaluation of carboplatin in tumor-bearing cats: a Veterinary Cooperative Oncology Group study.", J Vet Intern Med 22 (1): 83-8
- ↑ Martinez-Ruzafa I, Dominguez PA, Dervisis NG, Sarbu L, Newman RG, Cadile CD, Kitchell BE (2009 May-Jun), "(Abstract) Tolerability of gemcitabine and carboplatin doublet therapy in cats with carcinomas.", J Vet Intern Med 23 (3): 570-7
- ↑ Mark Goodfellow et al. (June 2006), "A retrospective study of 90Strontium plesiotherapy for feline squamous cell carcinoma of the nasal planum", Journal of Feline Medicine & Surgery 8 (3): 169-176, DOI:10.1016/j.jfms.2005.12.003
- ↑ Enrico P. Spugnini et al., "(Abstract) Electrochemotherapy for the treatment of squamous cell carcinoma in cats: A preliminary report", The Veterinary Journal 179 (1): 117-120, DOI:10.1016/j.tvjl.2007.08.011