in 1986. Dr. Yamamoto has since worked with Fort Dodge
Animal Health to develop an effective vaccine, resulting in the
USDA approving the first FIV vaccine in early 2002. Take these
steps to protect cats from FeLV and FIV, and reduce their risk of
associated cancers:
Keep cats indoors to reduce exposure from infected cats.
Quarantine and test new cats before introducing them to
resident cats
Consider FeLV and FIV preventive vaccinations for high-
risk cats—those adopted as strays, from shelters, living in
multicat households, and cats al owed outdoors.
Diagnosis
We often are anxious to get that “thing” removed from our cat
as quickly as possible, and the key to successful treatment is
early intervention. But saving time and cost by removing the tumor
before knowing the diagnosis can be dangerous, cautions Nicole
Ehrhart, VMD, a cancer surgeon at Colorado State University.
“You may disrupt tissue planes that might have been barriers for
spread of that tumor,” she says. “What could have been a
perfectly curable cancer with just surgery alone has been
compromised.” Without an advanced diagnosis, a hurried
surgery could result in spreading the cancer so it’s harder to treat,
or cannot be treated at al .
She says the best first step in diagnosing lumps is a needle
biopsy. Usual y no anesthetic is required, and it involves merely
inserting a needle and withdrawing a few cel s. “They look at them
on a slide or send off to a pathologist,” says Dr. Ehrhart. The
needle biopsy offers a good indication if caution is needed with
further tests—perhaps taking just a tiny piece of the tumor for
laboratory analysis. That not only identifies the cancer, but also
“stages” the tumor so the doctor knows how advanced it is and
can best recommend treatment options. When the cancer is on
the inside, an ultrasound, X-ray or other imaging technique may
be used to locate the tumor. A newer technique cal ed
lymphosyntigraphy injects radioactive tracers into the body.
Cancer cel s tend to absorb these compounds, which makes
them easier to locate.
A detection technique from human medicine, cal ed TRAP
(Telomeric Repeat Amplification Protocol), is now available for
veterinary use. The test detects telomerase, an enzyme that helps
cancer cel s recreate themselves indefinitely. Activity of
telomerase appears to be a unique feature of noncancerous
tumor cel s that turn into malignant cancers, says Dr. Kitchel .
Since normal cel s don’t usual y produce the enzyme, its
presence is an indication of cancer. Dr. Kitchel ’s study on cats,
published in the American Journal of Veterinary Research,
showed the presence of telomerase activity in twenty-nine of
thirty-one malignant tumors, and in only one of twenty-two benign
tumors studied over a two-year period. She hopes that an in-
house veterinary test kit for early detection of cancer wil become
available for local practitioners in the near future.
Once cancer has been diagnosed, owners have several
decisions to make. Although that can be scary and emotional y
draining to you, your cat won’t know why you are upset. She feels
the same as she did yesterday, and isn’t worried about the future.
Also, Dr. Ehrhart says that cancer is almost never a physical
emergency so you should careful y discuss the options with your
family and veterinarian and figure out what you want to do.
Having a good relationship with your cat’s doctor is very
important because you can ask questions and feel comfortable
taking her advice. Dr. Kitchel says oncologists must be able to
temper their clinical knowledge with empathy for the patient. “It
takes both to be good at this job,” she says. Part of the doctor’s
role is to help you make the best choice for your cat’s individual
situation. “What’s right for you might not be the right choice for the
next person,” says Dr. Ehrhart. “We wil support whatever
decision you make.”
Flexibility is built into treatment plans because not al owners
have the same goals for their cats. “Some clients want to cure the
animal of cancer,” says Dr. Kitchel . That al ows the doctor to offer
to live until kids come home from col ege to see him in the
summer,” she says.
No matter what the goal, though, nobody wants the treatment
make the cat feel bad. “These animals should feel well during
therapy, they should feel well after surgery, they shouldn’t feel
worse. We have the ability to make them feel good every single
day,” says Dr. Ehrhart.
Treatment
People need to understand that cancer is control able, and
sometimes it is even a curable disease, says Stephen J.
Withrow, DVM, director of the Animal Cancer Center at Colorado
State University. “You don't have to cure to heal. There's always
something that can be done to improve quality of life.” He says
that cure rates for malignant tumors in pets are 25 percent to 30
percent. In human medicine, it's 40 percent to 50 percent for
adults and 70 percent to 80 percent for children. “Cancer is more
curable than commonly treated diseases like diabetes and heart
failure.”
Veterinary oncologists use the same treatments to remove,
shrink, or stop the cancer growth as human doctors do. Surgery,
radiation, and chemotherapy are employed singly or in
combination, with the goal of keeping normal tissue untouched.
Several new therapies are also available that may help.
Dr. Kitchel says it’s hard to say what’s most common or
“normal” for cancer therapies because each patient is different.
Trial and error is often the name of the game because it’s not
possible to predict how every cat wil react. “If it works for this
patient, we keep going. If it makes the animal il and the quality of
life is diminished, we have to get off it,” she says. There are many
options, so it’s never an either/or situation. If one therapy doesn’t
work, there’s always another option to try.
Surgery
Surgery is the most common cancer therapy for pets. “Surgery
is sort of a two-edged sword,” says Dr. Ehrhart. “It has the
potential to cure more cancer than any other therapy that we
used, especial y single-modes of therapy. But at the same time, if
it’s used improperly it has the potential to harm you.” She strongly
urges owners to seek the advice of a cancer specialist before
beginning treatment.
Tumors can be removed with advanced techniques such as
lasers and noninvasive arthroscopic technology. Cancer is nearly
impossible to cure using surgery alone, though. Surgery often
disturbs and may distribute cancer cel s to other locations. Also,
leaving behind even a single cancer cel could al ow the tumor to
return. In most situations where surgery is used, it is fol owed by
chemotherapy, radiation, or other therapies.
Radiation
Surgery isn’t the best choice when a tumor is near vital
organs or nerves that also may be damaged, or on the face,
where little extra tissue is available. For these tumors, radiation
therapy often is used.
Intense X-rays are shot into the malignancy to kil the cel s.
Conventional beam radiation can’t tel the difference between the
cancer and normal tissue, and can cause damage these areas
as wel . Human cancers treated with radiation therapy tend to be
near other sensitive tissues such as the lungs or intestines. That’s
why human cancer patients treated with radiation often suffer
severe side effects, such as nausea and hair loss. These side
effects are rare in cats because the pet’s tumors typical y are on
the head or neck, far from sensitive organs. Occasional y cats
temporarily lose their appetite or shed whiskers. Radiation cures
up to 80 percent of some kinds of cancers. It works extremely wel
on skin and bone marrow cancers.
A concern with radiation is that cats must be anesthetized so
the X-ray to be aimed to the right target. Repeated treatments
are necessary—often twice a week for six to eight weeks—so
repeatedly giving anesthetic to senior cats is a potential problem.
New kinds of linear accelerators (radiation machines) have been
designed to better target the tumor while sparing normal tissue.
They may incorporate CT scanners to help “see” the tumor in
three dimensions and better plan the treatment, such as the ones
available at Washington State University and Tufts University.
University of Florida veterinarians and scientists created a
stereotactic radiosurgery technique using a special y designed
medical linear accelerator in conjunction with a three-dimensional
ultrasound guidance system. This treatment can pinpoint
radiation beams at tumors and avoid damaging normal tissue.
Instead of the conventional repeated therapy, it uses a one-time
extremely high radiation dose instead of repeated sessions over
a period of weeks. That means cats only need anesthesia one
time rather than several. It costs roughly the same amount as
traditional veterinary radiation therapy.
Chemotherapy
Chemotherapy drugs are designed to poison cancer cel s
that have spread throughout the body. Chemotherapeutics may
be administered as pil s, or injected intravenously. They are often
used after surgery to kil any stray cel s left behind.
Most chemotherapy drugs come from the human arsenal.
There’s no standard treatment for a given cancer, says Dr.
Kitchel , and different oncologists may have their own favorites.
Drugs may be used alone or in combinations, and prices range
from expensive to very reasonable.
Since chemotherapy drugs are usual y dosed by the animal’s
weight, the smal size of the cat makes this form of treatment
pretty economical. But if the first drug you try doesn’t work, it’s not
the end of the world. “Chemotherapy is not like jumping off a cliff,”
says Dr. Ehrhart. “You can do a reduced dose the next time or
change drugs. There are many choices.”
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. Cel -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 especial y careful with geriatric patients when we
try to treat them,” says Dr. Kitchel . “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 wel as other variables. Most cats weigh less than twenty
pounds, so the smal dose needed (often measured in
mil igrams 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 mil igram (wholesale).
Carboplatin (Paraplatin), an analogue of cisplatin, is
widely used in cats, and an average wholesale cost is
$1.80 per mil igram.
Doxorubicin (doxorubicin hydrochloride) is a type of
antibiotic that also has activity against certain
cancers. Average wholesale cost is approximately
$2.30 per mil igram.
Other Options
Various cancers respond better to therapies such as
cryosurgery, which freezes and destroys localized, shal ow
tumors using (usual y) liquid nitrogen. Cryosurgery ideal y treats
skin cancers of the face. Cats with white faces are most prone to
sun-induced cancers of the nose and ears, and especial y benefit
from this form of therapy.
A unique new treatment, photodynamic therapy (PDT),
employs sensitizing agents that act like chlorophyl , which cancer
cel s preferential y absorb. Once the agent has been absorbed,
the cancer is treated with laser light. That causes energy to be
released inside the sensitized cel s, kil ing 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 cel carcinoma, a
type of skin cancer, which is amenable to treatment with PDT.
PDT availability is limited to a smal number of veterinary
teaching universities, including University of California-Davis.
The opposite of cryosurgery is heat therapy
(hyperthermia). Basical y, the treatment cooks the cancer to kil it,
using sound waves that penetrate the body at specific depths and
dimensions.
Ongoing
studies
in
hyperthermia
cancer
applications continue at University of Il inois and North Carolina
State University-Raleigh.
Gene therapy remains experimental but is the latest
innovation in veterinary cancer treatments. For example, studies
on genetical y 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 cal ed
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 a specific
spectrum of nutrients might be able to prevent the weight loss
associated with cancer.” Better nutrition means their immune
system wil have a better chance to fight the cancer.
In conjunction with Hil ’s Pet Foods, Dr. Gregory Ogilvie at
Colorado State worked to create a commercial canine diet
designed to counter the metabolic changes caused by cancer.
Studies are underway to develop a cancer diet for cats that works
as wel as Prescription Diet n/d (for dogs), which is relatively low
in simple carbohydrates, and relatively high in DHA, a
polyunsaturated fatty acid thought to prevent the growth and
spread of tumors.
Dr. Ehrhart has launched a similar study in cats at the
University of Il inois to determine how diet might affect cancer
therapy. “Cats are very different because they’re obligate
carnivores, while dogs are omnivores—we can extract human
data and apply to the dog and vice versa, but cats are total y
different creatures. The way cats assimilate nutrients is very
different.” She seeks feline cancer patients to participate in the
study—contact Dr. Ehrhardt at the University of Il inois for further
information about enrol ing your cat. Patients admitted to the
program receive free food and rechecks, but owners fund the
cancer treatments themselves. “It would be people who have
chosen to do the cancer treatment already, and also elect to
participate in the study,” says Dr. Ehrhart
Feeding the cancer patient wel offers important support and
goes hand in hand with other therapies such as chemo or
surgery, says Dr. Wynn. “We think homemade diets real y help
them feel better. Sometimes putting them on a homemade diet
gives them kind of a boost—whether its phytochemicals, whether
it’s a change in the amount of fats and starches, we don’t real y
know.” Cats fed homemade diets seem to enjoy a better quality
of life, says Dr. Wynn, but says, “This is something that I wouldn’t