The goal of
cancer treatment in the veterinary patient
is to prolong good quality of life for as
long as possible. Quantity of life is
meaningless without quality. Because quality
issues are vague and changeable, it is easy
to focus instead on quantity because that is
a specific, well-defined goal. It is
important to keep these two factors in
balance. Your veterinarian should provide
perspective and be objective and
well-informed about cancer, it's treatment,
and how it is likely to affect your pet. On
the other hand, you know your pet the
best. The veterinary staff sees your pet for
perhaps a few hours a week in a hospital
setting, while you and your family are with
your pet at home on a daily basis.
Cancer
treatment usually involves side effects,
which can affect a pet's quality of life.
The degree of side effects that are
tolerable depend on the goal and expected
outcome of treatment. If our hope is for a
cure or control of cancer (which in
veterinary medicine usually means one year
or longer), then we may be willing to
tolerate treatment side effects with a
higher risk, severity, and duration. Several
days or weeks of decreased quality seems
reasonable in exchange for many months of
good quality of life. However, if we believe
a cancer is incurable or impossible to
control, then our goals become those of
palliation, which is an attempt to maintain
or improve quality of life without
attempting to prolong it. We are unwilling
to accept anything but minimal treatment
side effects because the treatment should
not be worse than the disease. Palliative
care focuses on supportive measures such as
controlling pain and infection, and
providing adequate nutrition. Every owner
and veterinarian will have their own opinion
as to what constitutes acceptable and
unacceptable risks and side effects. It is
important to thoroughly discuss these
concerns with your veterinarian so that
together you can work towards a common goal.
Because we
cannot ask our pets how they feel, we have
to rely on their behavior and from this
infer quality of life. Measurements of
quality of life have been developed by
veterinary oncologists. For example, the
Animal Medical Center in New York City
developed a "Performance Scale" that allows
both the pet's family and the veterinarian
to assess overall quality of life. It
considers 5 factors that affect an animal's
ability to carry on its normal activities.
They are:
- alertness/mental status
- appetite
- weight/body condition
- activity/exercise tolerance
- elimination
Not only is
this assessment a good indicator of how your
pet feels overall, it also provides useful
medical information. In general, animals
that score high (i.e., have close to normal
behaviors) tend to tolerate treatments well
and do better overall than animals who score
lower on the scale.
Quality of
life means different things to different
people. For some people it is their pet's
chasing a ball or greeting them at the door.
For others, it is simply knowing that pets
are eating and sleeping through relaxing,
painless days. One of the difficulties in
evaluating your pet's quality of life is
that it can decline gradually. For someone
living with a pet there may be no obvious
daily changes, while to someone who only
sees your pet every few weeks or months
there could be dramatic change. Because of
this, we encourage owners to establish and
document their own personal "minimum
standards" of quality of life for their pet
at the start of cancer treatment. For
example, it might be a pet's lack of
interest in eating or going on walks. It
might be a pet's struggling to breathe or
inability to "get comfortable". Often, it is
a pet's inability to respond to his owners
or his struggle to muster even a small
gesture of affection. Thinking about these
issues and discussing them with your family
and veterinarian early in the course of
therapy can help with difficult decisions
later on, such as discontinuing treatment or
electing euthanasia.
There often
comes a point in the treatment of our
veterinary cancer patients when we have
exhausted all reasonable treatment options,
and there is a low probability for quality
of life in the future. We must remember that
just because a treatment is technically
possible does not mean that it is the best
thing for our patient. We are then faced
with euthanasia as the last treatment
option. Just as we have intervened in the
pets life by providing aggressive medical
care in an effort to improve and prolong
quality of life, we intervene when these
methods are no longer effective so that we
do not prolong needless suffering. It is the
last act of kindness we can offer.
Palliative therapy can be thought of as "comfort
care". It is treatment intended to maintain a good
quality of life for patients in which long-term
cancer control is not possible. Palliative radiation
therapy can be used to control the symptoms
associated with many localized tumors that cannot be
treated by other methods (such as surgical removal).
These symptoms include pain, bleeding, and decreased
function.
Radiation is usually combined with
anti-inflammatory and pain medications to maximize
the relief of cancer-related symptoms. The goals of
palliative therapy are to provide symptom-relief,
and not to increase survival time or cure the
cancer. Radiation therapy is particularly useful in
alleviating pain associated with tumors that are
arising from, or invading into bone. About two
thirds of patients have moderate to significant
improvement, and the effects can last for a few
weeks to several months. Decrease in symptoms can
occur as quickly as several days after the first
treatment, or it may take a few weeks before
improvement is seen.
Palliative radiation involves delivering a few
large doses of radiation over several weeks. The
typical plan involves giving three treatments on
days 0, 7, and 21 (in other words, two treatments a
week apart, followed by a week of rest, and then a
third treatment if indicated). In most cases,
palliative radiation therapy is a one-time course of
treatment and cannot be repeated. Each treatment
requires light anesthesia because the patient must
be completely still during the procedure—there is no
pain or discomfort associated with delivery of the
radiation. Your pet must have no food after 8 PM the
night before each treatment (water is okay) to
insure an empty stomach prior to anesthesia.
Patients are treated as outpatients, with each
treatment requiring about 2-3 hours at the
Veterinary Hospital of the University of
Pennsylvania. This time includes preparation for
anesthesia, treatment delivery, and recovery. The
radiation is focused on the tumor, and the fur in
this area will be clipped and pen marks used to
outline the treatment area. A small area on a leg
will also be clipped for an intravenous catheter
(I.V.) used during the anesthesia. Your pet may be a
little groggy or sedate for several hours after
going home, and should be kept quiet and have
limited food and water until fully recovered.
Side effects are minimal, and are limited to the
area receiving radiation. They start after about
three to four weeks from the first treatment and
last for a few weeks. The radiated area will be pink
to red and hairless and there may be some mild
flaking or crusting of the skin. Treatment of these
side effects include the use of topical medications
and preventing your pet from licking, rubbing, or
scratching at the treated area. Eventually the skin
in this area will become very dark to black, and
some sparse hair may regrow. Long term side effects
(such as the risk of non-healing wounds) take many
months or years to occur, and are typically not a
problem because most patients undergoing palliative
care have a life expectancy of less than one year
due to their cancer.
