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Cancer is the uncontrolled growth of cells on or
within the body. They are either localized to one part of the body as a
visible mass (tumor) or spread throughout (metastasis). Cancer is common
in pet animals such as the dog or cat and the rate increases with age.
Dogs get cancer at roughly the same rate as humans, while cats get fewer
cancers. In one survey, approximately 1 of every 250 dogs and cats
developed cancer during their lifetime and cancer accounted for almost
half the deaths of those pets over 10 years of age. Since the cause of
cancer is not known, prevention is difficult. The exception is breast
cancer which is largely preventable with early neutering.
THREE RULES FOR MANAGING THE CANCER PATIENT
RULE 1: GET A DIAGNOSIS
Biopsy, Biopsy, Biopsy.
A
veterinarian can never give an accurate assessment (prognosis) or develop an appropriate
treatment plan for the tumor-bearing pet without a complete diagnosis. Knowing the
histologic type of tumor gives the veterinarian a sense of the natural behavior of the
tumor (how it will grow, where it will go).
RULE 2:
EVALUATE THE
ENTIRE PATIENT
Remember, there is a pet attached to
the tumor. Many times we forget the BIG PICTURE. A thorough evaluation
of the pet includes obtaining appropriate laboratory information (blood counts, blood
chemistry, urinalysis) and survey radiographic images of the thorax, abdomen, and the
tumor site. Additional information may be required depending upon the known
natural behavior of the tumor (remember that biopsy you took in Rule 1 - it's extremely
important). These tests may include a bone marrow aspirate, electrophoresis of serum
or urine, buffy coat smears, more biopsies, ultrasound of a body area, nuclear imaging,
serology, virology, or many other procedures.
A
thorough knowledge of the entire patient is necessary BEFORE an appropriate therapeutic
plan can be presented. The goal is to identify or rule out the presence of concurrent
illnesses and tumor metastases to regional lymph nodes or other body tissues (lungs,
liver, skin, bone, for example). This information is essential not only for
treatment planning but also to determine treatment success or failure.
RULE 3:
DEVELOP AN
APPROPRIATE TREATMENT PLAN
Determine your goal.
Is cure
possible or should more emphasis be placed on quality of life (or can both be
achieved? In general, there are 3 choices facing every family with a
tumor-bearing pet:
Choice 1:
What Is Best
For The Cancer?
In today's world there are basically
2 ways to treat cancer, remove the tumor (with surgery and getting cancer-free edges all
around the tumor) or destroy the tumor's ability to grow (using radiation, chemotherapy,
or both; maybe in combination with surgery). There are a number of other innovative
strategies under development such as immune stimulants, nutriceuticals, and tumor vessel
growth inhibitors, but their true ability to control cancer is not yet known or proven
(nor the best way to use them in managing cancer patients - in humans or animals). Veterinarians cure a large majority of cancers
with surgery. Those that cannot be completely removed and have not yet spread to
other body sites can be cured with additional measures (radiation, chemotherapy, etc) no
differently than in people. Common concerns
are about "how my pet look without a leg, a lower jaw, a rib?" or "how much
is radiation therapy, and what are the side effects?". Every pet owner whose
loved one has cancer faces these and other questions. There are no easy
answers. However, if the objective of the planned treatment is to attempt a cure of
the cancer, surgery with or without radiation has to be strongly considered.
Talk to
a Veterinary Oncologist!
Choice 2:
What Is Best
For The Pet?
Remember, for most families, quality
of life for their pet is more important than the pet’s remaining quantity of life. Remember, cancer is "uncontrolled
growth". If the abnormal growth cannot be removed from the body or controlled
with localized radiation therapy, it is entirely appropriate the use medications
(anticancer drugs, nutritional supplements, pain control medications, anti-cough or
anti-nausea medications, and many others) to maximize the quality of life of the
cancer-bearing pet. To "control"
the "uncontrolled growth" of cancer, anticancer drugs (chemotherapy) are
used. The goal of chemotherapy is not to cure the cancer but to slow down the
growing phase of the cancer. Yes, many cancer cells are killed with chemotherapy and
tumor shrinkage can be observed; however, it is impractical for most situations to expect
that every cancer cell will be killed by any chemotherapy protocol or strategy.
With
chemotherapy, the more drugs that are used, the more often they are given, the more cancer
cells that are killed. Therefore, to significantly decrease the burden of cancer and
increase the lifespan of the pet, combination chemotherapy protocols that prescribe drugs
every 2, 3, or 4 weeks throughout the remaining lifespan of the pet should prolong the
pet's survival. Obviously, most chemotherapy
drugs do not know a normal cell from a cancer cell, thus, more drugs given more often
results in the possibility of more side effects. If the goal is to provide more
quality of life than quantity of life, a fewer number of drugs at lesser doses given less
often will still slow down cancer just not as much!
Choice 3: What Is Best For The Family?
It is entirely appropriate not to
treat cancer in pets. In fact, in some situations, we should not recommend cancer
therapy. However, just because we are not controlling the cancer does not mean we
cannot provide the pet a comfortable life.
When
this cannot be accomplished, we should strongly urge pet owners to consider the choice of
euthanasia. It is important to have a support group during this process. Please rely upon the good advice of family and
friends during this difficult time. In addition, there are many pet owners who
are willing to share their positive and negative experiences. It is essential to provide adequate nutritional
support, pain control, and other measures that ensure the pet's good quality of life. Quality of life is very subjective.
Everyone
has an opinion. Ask for opinions and listen to them!!!! Then make your best
choice. Hindsight is 20:20 but if you follow the above rules - get a diagnosis and
evaluate the whole patient - then you should have plenty of information to make the best
choice available at that time.I hope this information provides some
insights towards our approach in managing the veterinary cancer patient. Always consult with a Board Certified Veterinary
Oncologist. Use a team approach and allow your pet owners to participate in the
team. Cancer is a battle that can be won -
engage into the fight, but realize when it is time to retreat.
Drs. King, Carreras and Endicott are available to consult
with your veterinarian if they have oncology cases requiring further diagnostic
workup or treatment.
Please call if we can help:
Phone: 713-693-1166
Fax: 713-693-1167
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