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“I’m feeling a lump in Annie’s abdomen”.
As a veterinarian, I’m sometimes forced to give unwelcome
news. I could not have
uttered words more devastating, however, than those just delivered to
Christoph and Ellen Franzgrote. A
year ago, they watched their cat Mia succumb to lymphosarcoma, a cancer of
the lymphoid tissues. Mia
couldn’t abide her chemotherapy and quickly surrendered to the disease
at the age of five. Today’s
routine wellness check on Mia’s daughter, Annie, yielded an abdominal
mass.
The prevalence of feline cancer is increasing.
Advances in veterinary medicine have allowed cats to live longer,
and cancer is generally a disease of older animals. This is the fateful
price cats must pay for living longer.
Cancer is unrestrained cell division and growth.
Normally, cell division is tightly regulated.
When a single cell undergoes a series of genetic mutations, cancer
may arise, causing cell division to become unregulated, resulting in a
tumor. While the cause of
most cancers remains unknown, environmental agents can induce cancerous
changes in cells, such as viruses, chemicals, radiation, and some
hormones. The effects of
these agents can accumulate over time, explaining why cancer more commonly
affects older animals.
Another word for cancer is neoplasia (“new growth”),
and tumors are sometimes referred to as neoplasms.
Tumors are classified as benign or malignant. Benign tumors remain at their original site.
Malignant tumors can invade surrounding tissues and gain access to
the bloodstream or lymphatic vessels, and then be transported to nearby
lymph nodes or other part(s) of the body.
This is called metastasis, and is commonly how cancer spreads.
The word cancer generally implies malignancy.
While benign tumors are generally less worrisome and malignant
tumors are more troubling, this distinction isn’t always clear-cut. A seemingly benign tumor may behave malignant clinically,
impinging on nearby structures and becoming impossible to remove or treat.
Cats are susceptible to a variety of cancers.
Among the most devastating are lymphosarcoma, squamous cell
carcinoma, and mammary (breast) cancer.
Lymphosarcoma is a cancer arising from lymphoid tissues
involving any organ. Affected
cats ranges, on average, from 2 to 6 years, although any age cat is
susceptible. Infection with
the feline leukemia virus increases the risk of developing lymphosarcoma.
This is especially true of younger cats.
Older cats that develop lymphoma are less likely to be concurrently
infected with the feline leukemia virus.
Lymphosarcoma is often categorized by anatomic location.
The five types are mediastinal (involving structures inside the
chest), alimentary (digestive system), multicentric (the lymph nodes),
leukemic (the bloodstream), and extranodal (other organs, such as the
kidneys, eyes, nervous system, nasal cavity, and skin).
In cats, the most common sites are the gastrointestinal tract, the
mediastinum (structures in the chest such as the thymus and associated
lymph nodes), the liver, spleen, and kidneys.
Fortunately, lymphosarcoma is fairly responsive to chemotherapy.
Squamous
cell carcinoma (SCC) accounts for 15% of all feline skin tumors.
These tumors usually involve light or unpigmented skin.
Sun exposure increases the risk of developing SCC.
Solar-induced SCC is referred to as “actinic” SCC. The most
common locations are the hairless area of the nose, the eyelids, and ears.
Older cats are at higher risk; the mean age for affected cats is 12
years. Siamese cats, with
their pigmented skin, are less likely to develop SCC than other breeds.
SCC of the skin is often amenable to treatment.
Dr. Tim Rocha is a board-certified veterinary oncologist in New
York City who has had good success treating SCC of the skin.
“Except in advanced cases, we have several therapeutic
options that all have good to excellent success rates.
Surgery, radiation therapy, and intralesional chemotherapy (where
the drug is injected directly into the tumor) have all been shown
effective in treating this cancer”, says Dr. Rocha. SCC
may also affect a cat’s mouth. This is often disastrous, as oral SCC is
much worse than the skin form. “Unfortunately”, says Dr. Rocha. “95%
of these oral SCC cases are diagnosed only after the cat shows dramatic
changes in appearance, such as swelling of the jaw or face, severe weight
loss, or blood in the mouth”.
Treatment
for oral SCC is often unrewarding. “It
is sad that we have yet to identify any treatments that are reliably
helpful.” Surgery offers
the best chance for survival, but most of the time it has progressed too
far. “If a SCC is removed surgically in it’s entirety, a cat
may become one of the rare 5% of cats that beat this diagnosis”, says
Dr. Rocha.
Mammary
tumors tend to develop in older cats. They account for 17% of neoplasms in
female cats. Spaying dogs
before their first heat lessens the risk of future mammary tumor
development, and this also holds true for cats.
Rarely, male cats will be affected.
In cats, the behavior of mammary tumors is very different compared
to dogs. While roughly half of canine mammary tumors are malignant, at
least 80% of feline mammary tumors are malignant. Siamese cats have at least twice the risk of developing
mammary tumors compared to other breeds, and they tend to be affected
earlier, reaching a plateau at 9 years of age.
More than half of affected cats show multiple gland involvement.
Unfortunately, mammary cancer may spread to the lungs quickly,
making the prognosis guarded or poor.
Surgery is the best treatment option for feline mammary tumors. Dr.
Kathy Kazmierski, a veterinary oncologist at Garden State Veterinary
Specialists in New Jersey, says that the most important prognostic factor
for survival is the size of the tumor at diagnosis and removal.
“Tumors that are less than 2 centimeters big are much better than
those that are 3 centimeters or greater”, she says.
“Follow-up chemotherapy is often recommended”, says Dr.
Kazmierski, “but there are not enough cases studied to know if that
offers a true survival benefit”.
To make a definitive diagnosis of
cancer, tests must be performed. Blood
work, x-rays, and ultrasound provide a great deal of information, but
ultimately, most cases require a biopsy to confirm the diagnosis.
Blood tests on Annie Franzgrote showed no cancer cells in
the circulation, and she tested negative for the feline leukemia virus.
Further tests were needed to characterize the abdominal mass.
X-rays were taken, and the results were highly suggestive of an
intestinal tumor.
Once cancer is diagnosed, there are three common treatment
options: surgery,
chemotherapy, or radiation. Surgery
affords the best chance a cure, by removing the affected tissue. Surgery is curative only if the cancer hasn’t already
spread and if the affected area can be removed completely. For cancers like leukemia, which involves the bloodstream,
surgery is obviously not an option.
Radiation is an option for localized tumors that cannot be
treated surgically, or were treated surgically but all cancerous tissue
couldn’t be removed. Radiation
injures rapidly dividing cells, such as cancer cells.
When irradiated, cancer cells can no longer divide and spread, so
they die. Some cancers are
very susceptible to radiation treatment, while others are resistant.
Chemotherapy is another common option, especially for
cancers involving many body sites, or sites that aren’t disposed to
surgery or radiation. While
many veterinary chemotherapy drugs are exactly the same as those used in
humans, they’re not given with the same expectations.
Chemotherapy for animals is not intended to be curative.
The goal is to reduce the number of cancer cells and slow the
progression of disease for as long as possible, while maintaining good
quality of life. As such,
most cats tolerate chemotherapy very well. Chemo drugs are potent, however, and cats must be monitored
for side effects such as vomiting, diarrhea, and poor appetite.
Generalized hair loss is uncommon, but shaved hair is slower to
grow back, and cats may lose their whiskers.
For Annie, surgery afforded the
best chance of a cure. At
surgery, a discrete tumor affecting the small intestine was discovered. A
nearby lymph node was enlarged. The
tumor was removed, and the lymph node was biopsied.
Annie recovered uneventfully.
Two days later, the pathologist’s report arrived: lymphosarcoma,
with the disheartening news that cancer cells were detected in the lymph
node. The tumor had spread.
Surgery alone wasn’t going to be effective.
The Franzgrotes elected not to attempt chemotherapy, due to
Annie’s nature. “Annie
was very sensitive, and the idea of her living in fear when we approached
her was unacceptable”, says Christophe.
After much discussion, it was agreed that Annie would live the
remainder of her life at home, and euthanasia would be considered when the
quality of life was no longer satisfactory.
“We concentrated on lavishing her with care, giving her anything
she desired”, notes Ellen. Annie did well for several weeks until the
cancer spread to her kidneys, causing them to fail.
With her condition rapidly deteriorating, the Franzgrotes elected
to put her to sleep, 10 weeks after the diagnosis.
The decision to euthanize a pet with cancer is often the
most difficult choice a pet owner makes.
Owners must strike the delicate balance between waiting too long
and having their cat suffer or be in pain, and deciding too soon and
feeling as if they’ve deprived themselves and their cat even a day or
two of reasonably comfortable life. Frequent
consultation with the veterinarian and clear communication between family
members often leads to the proper determination as to when it’s time to
bid farewell.
The single most important prognostic factor for successful
treatment of cancer is early detection.
As veterinarians and cat owners develop an increasing awareness of
cancer, earlier detection becomes more likely.
Unfortunately for Annie, her cancer had spread before it was
detected.
As luck would have it for the Franzgrotes, our hospital
stumbled upon a somewhat sickly stray kitten.
Christophe and Ellen spied little Roopoo as they passed by our
front door, and it was love at first sight.
Once nursed back to health, they took him home, where he instantly
clicked with Annie’s forlorn housemate, Lucie.
They now spend their days wrestling and napping together.
“After our past heartache, nothing gives us more satisfaction
than the company of these two happy and healthy cats”.
What to do if you feel or spot a lump or bump on your cat
Petting and stroking your cat isn’t just about affection.
It’s also a good way to monitor your cat for the development of lumps
and bumps. Lumps on the back and the legs are more easily felt.
Conscientious pet owners should feel all over the cat, especially
in uncommon areas like the mammary glands, the mouth, and the underside of
the neck. If you feel a lump or bump on your cat, take note of several
things:
·
Size
·
Location
·
Texture (soft or firm)
·
Sensitivity (does it bother your
cat when you touch it)
·
Other characteristics (Is it
ulcerated? Oozing? Bleeding? Associated foul smell?)
While the
vast majority of lumps and bumps are harmless, it takes a professional
assessment to be sure. In
general, benign lumps grow more slowly and often have well-defined edges
to them. If you choose to
monitor the lump yourself, be vigilant.
All big tumors begin as small tumors. Don’t overlook them.
If the lump exhibits any significant changes – a sudden increase
in size, texture, or any other characteristic - see your veterinarian
immediately.
According to
the Veterinary Cancer Society, there are some common signs of cancer in
animals that owners can look for.
·
Abnormal swellings that persist or
continue to grow
·
Sores that do not heal
·
Weight loss
·
Loss of appetite
·
Bleeding or discharge from any
body opening
·
Offensive odor
·
Difficulty eating or swallowing
·
Hesitation to exercise or loss of
stamina
·
Persistent lameness or stiffness
·
Difficulty breathing, urinating,
or defecating
Other
signs, such as pain, fever, anemia, drinking too much water, producing
excessive urine, and ravenous appetite may also be signs of cancer,
depending on the specific tumor and the effects it has on the body.
Updated 2/9/06 |
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