An Overview of Cancer
Cancer is caused by uncontrolled and purposeless growth of cells in the
body. Other terms for cancer are malignancy, tumor and neoplasia. Cancer can
arise from any tissue in the body so there are many types of cancer.
Some forms of cancer have the ability to spread to other sites
in the body which are often far from the original site. This happens when
cancer cells enter the blood or lymph vessels and are then carried to other
organs. Cancers with this type of behavior are considered malignant. Often,
it is the spread of a cancer that causes the greatest problems. When a
cancer has spread in this fashion, it is said to have metastasized. Some
cancers lack the ability to metastasize, but may cause significant damage
due to growth and invasion into local tissues. Tumors that do not
metastasize and are not invasive are considered benign. Tumor is a general
term for cancer whether it is benign (“good cancer”) or malignant (“bad
cancer”). Oncology is the branch of medicine dedicated to the study of
cancer, and the people treating your pet at WSU are Oncologists and Oncology
nurses.
Tumor Evaluation (Work-up): Tumor Staging
The first task for the veterinarian is to determine the extent of the
tumor which is a process called tumor staging. Staging information is
vital for several reasons including:
1. determination of your pet’s prognosis (i.e., the expected
outcome for your pet from the illness) and,
2. formulation of a plan for treatment.
To gather information that can help to determine the extent of
the cancer, your veterinarian will need to evaluate your pet by several
methods. These usually include blood tests (e.g., blood count, chemistry
profile), urinalysis, radiographs (x-rays), tissue aspirate (a sample
taken with a fine needle) and biopsy. Tests which your veterinarian may
have performed might be repeated at WSU due to the changing nature of
your pet’s illness. In addition, as indicated for specific patients,
other testing procedures may include: ultrasound, specialized radiologic
studies (e.g., CT scan, dye contrast studies), bone marrow aspirate,
lymph node aspirate, endoscopy (direct examination of the stomach, colon
or bronchi with a specialized scope), and immunologic studies. It is
important to note that medicine is not an exact science and despite
these staging procedures, it is still possible to fail to recognize
small sites of tumor or the presence of tumor in organs that are
difficult to study.
Once the tumor staging has been completed, your veterinarian
will better be able to discuss treatment options for your pet. The goal
of such therapy will also be discussed. Tumors that have metastasized
extensively are usually not curable. Therefore, the objective of therapy
for these animals is palliation (i.e., afford relief of signs without
providing cure, and possibly, prolong life). Localized tumors that are
not deeply invasive have the best chance to be cured.
Cancer Therapy
There are several types of therapy used to treat cancer in dogs and
cats at WSU. These include surgery, chemotherapy, radiation therapy, and
immunotherapy. For some tumors, treatment will consist of a single type
of therapy, while combination therapy may be recommended for other types
of cancer or for animals with a more advanced stage of disease. On
occasion, due to the rarity of a particular tumor, a precise treatment
recommendation may not be known. In an effort to test newer (and
hopefully more effective) forms of therapy, you may be asked to enroll
your pet in an investigative clinical trial. The purpose of such a trial
is to learn more about the specific type of treatment (that may be of
value to humans and other pets with cancer) as well as hopefully
providing a benefit to your pet. Only pet owners of animals with tumors
for which there is no effective treatment, or tumors that have not
responded to conventional treatment will be offered investigative
therapy for their pets.
Should You Treat Your Pet?
Treating animals with cancer is not appropriate for every pet owner.
It takes a strong commitment on the part of the owner. Therapy requires
frequent trips to the veterinary hospital and can be expensive. For some
forms of cancer treatment, once begun treatment is never stopped during
the animal’s life although the frequency of these treatments can be
decreased. Your veterinarian cannot do it alone since treating pets with
cancer is truly a team effort and the pet owner is on the team. It is
important for you to present your pet for treatment precisely when
requested to do so by your veterinarian since the timing of cancer
therapy is critical for obtaining an optimal outcome. In addition,
medicines to be given to your pet at home should be administered by you
exactly as instructed by your oncologist. Any abnormalities or problems
you encounter should be reported to your regular veterinarian or
oncologist promptly. Always feel free to ask questions and communicate
with us.
Keep in mind your veterinarian is as concerned about the quality
of your pet’s life as you are. The goal of the therapy is to keep your
pet happy and minimize discomfort. Although some animals may experience
transient discomfort from therapy, treatment of most pets with cancer
can be accomplished without major distress or detraction from your pet’s
enjoyment of life. Just because an animal has been diagnosed with cancer
does not mean its life is immediately over. Your commitment to your pet
and your veterinarians dedication to providing state-of-the-art care
will work together to keep your pet as happy as possible.
