Complete Care for Your Aging Cat - Amy Shojai [84]
Dr. Henry warns that some agents routinely used in dogs and people, such as 5-fluorouracil and cisplatin, produce fatal toxicity in cats. She says carboplatin may be used in place of cisplatin and given safely by intravenous infusion in cats. But treating with intravenous or oral medications can be difficult when cats are fractious and venous access port (VAP) implants can be helpful in these cases. Dr. Henry notes that the average cost for a VAP is less than $300 which may save money in the long term, when it replaces repeated catheter placements and/or sedations.
Anesthetic isn’t always concern with chemotherapy, but there are other risks involved. Cell-poisoning drugs must be metabolized and eliminated via the liver and kidneys, and old cats may not have the necessary capacity to deal with the strain. “We have to be especially careful with geriatric patients when we try to treat them,” says Dr. Kitchell. “When you treat with cancer drugs, there are risks. You can’t predict who’s going to be super sensitive. But if you’re going to cure with chemo, you do it and they never come out of remission. They stay in remission forever.
Bottom Line
Radiation therapy series costs about $2200
Chemotherapy costs varies, from very expensive drugs to quite reasonable ones, and depends on the dose required as well as other variables. Most cats weigh less than twenty pounds, so the small dose needed (often measured in milligrams per pound body weight) tends to limit the cost. For example:
Ifosfamide (Ifex) used against soft tissue sarcomas in cats, costs about 30 cents per milligram (wholesale).
Carboplatin (Paraplatin), an analogue of cisplatin, is widely used in cats, and an average wholesale cost is $1.80 per milligram.
Doxorubicin (doxorubicin hydrochloride) is a type of antibiotic that also has activity against certain cancers. Average wholesale cost is approximately $2.30 per milligram.
Other Options
Various cancers respond better to therapies such as cryosurgery, which freezes and destroys localized, shallow tumors using (usually) liquid nitrogen. Cryosurgery ideally treats skin cancers of the face. Cats with white faces are most prone to sun-induced cancers of the nose and ears, and especially benefit from this form of therapy.
A unique new treatment, photodynamic therapy (PDT), employs sensitizing agents that act like chlorophyll, which cancer cells preferentially absorb. Once the agent has been absorbed, the cancer is treated with laser light. That causes energy to be released inside the sensitized cells, killing the tumor but leaving normal tissue intact. PDT has particularly beneficial applications for certain skin cancers, oral tumors and bladder tumors. For example, cats are quite prone to squamous cell carcinoma, a type of skin cancer, which is amenable to treatment with PDT. PDT availability is limited to a small number of veterinary teaching universities, including University of California-Davis.
The opposite of cryosurgery is heat therapy (hyperthermia). Basically, the treatment cooks the cancer to kill it, using sound waves that penetrate the body at specific depths and dimensions. Ongoing studies in hyperthermia cancer applications continue at University of Illinois and North Carolina State University-Raleigh.
Gene therapy remains experimental but is the latest innovation in veterinary cancer treatments. For example, studies on genetically engineered tumor vaccines designed to target mouth cancers are being conducted by internist E. Gregory MacEwen, VMD, and his team at the University of Wisconsin.
Nutrition
Researchers have been examining how cancer changes the way the body uses food. Cats suffering from cancer often lose weight even when they maintain a good appetite—this is called cachexia. “There are metabolic changes you can detect in cancer patients that suggest they’re not able to use nutrition as effectively,” says Dr. Ehrhart. “This was first noticed in people, and then Dr. Ogilvie did his study looking at how