The Dog Cancer Survival Guide (19 page)

Carcinogens
: Carcinogens are cancer-causing agents, which can be found anywhere – in our food, in our water, in our air, and in our soil. Carcinogens are discussed in some detail in
Chapter 8
.

Cell
: Cells are the tiny “building blocks” of the body. They are so small that over 10,000 can fit on the head of a pin. Until a few years ago, science believed that once a cell committed to being a certain kind of cell – a heart cell, a liver cell, and so on – it could never change into any other kind. Recent evidence shows us that perhaps this is not entirely true.

Chemotherapy
: Historically, the word chemotherapy referred to the use of any chemical in any medical treatment. Today, it is used to describe the use of pharmaceuticals in a cancer treatment. Chemotherapy kills cancer cells in a variety of different ways, including: increasing damaging free radicals within cancer cells, damaging DNA, blocking cell division, interfering with cell metabolism, and increasing apoptosis. Often there is a blend of different processes leading to
cytotoxicity
. Chemotherapy drugs are usually administered intravenously or by mouth, depending upon the drug. Typically, the goal is to give the dog the
maximum tolerated dose
, although lower doses are used in
metronomic chemotherapy
. Dogs do not usually require sedation or anesthesia during chemotherapy treatments.

Chronotherapy
: Literally, “time therapy.” Most compounds (chemotherapy drugs as well as other agents) seem to have a time of day when they are at their most potent, with the fewest side effects. For example, one drug may be best at 10am, while another is best at 3pm. Chronotherapy is in its infancy in the U.S., but we’re learning more every day.

Clean Margins
: A biopsy is said to have “clean margins” when the pathologist does not see evidence of tumor cells in the margins of normal tissue examined during the
comprehensive margin evaluation
.

Complete Blood Count:
A very common test used to assist in diagnosis. It measures many aspects of the blood, including the numbers and types of white blood cells, red blood cells, and platelets. Also known as a CBC.

Complete Remission
: All measurable signs of cancer are gone. However, due to the inherent nature of systemic cancer, measurable signs are likely to return at some point in the future. See
remission
.

Comprehensive Margin Evaluation
: An examination performed by a pathologist to see if there are cancer cells along the margins of biopsied tissue. If there are cells on the edge of the tissue sample, there are likely some left in the dog, and another surgery or other treatment may be in order. If cells are present, the results are called
dirty margins
or “incomplete margins”; if the pathologist doesn’t find any microscopic tumor cells, the results are called
clean margins
or “complete margins.” Despite the use of the word “comprehensive,” a pathologist only looks at a couple of areas along the margins, not the entire margin. This is why
wide margins
are so important to prevent malignant tumor regrowth.

CT Scan
: CT stands for computed tomography, which is a medical imaging technique using two-dimensional
X-rays
taken in a series and digitally computed, or manipulated, so that a three-dimensional image of the inside of the body is formed. Each image shows a “slice”, also called a tomograph, of the body and provides more detail than X-rays or ultrasound. CT scans are usually only available in large veterinary or specialty hospitals. It’s important that the dog remains still during a CT scan, so heavy sedation or general anesthesia is usually required.

Cure
: When cancer is completely absent from the body, and is not expected to return at any time in the future, the patient has achieved a “cure.” I have seen dogs live long years past their prognosis, and I have also seen cancer disappear from bodies and never return. Unlike other areas of veterinary medicine, where we can say “this can be cured” or “this can be managed forever,” we cannot say this yet for
systemic cancer
cases. Until that day, I rely on conventional and outside-the-box treatments, in the hope that something – or more likely, many things together – will work for your dog. In the meantime, Dr. Ettinger and I both agree that it may be helpful to think of your dog’s cancer as a treatable, chronic condition, rather than a curable disease.

Cytotoxic
: Literally, “toxic to cells.” This word is used to describe cancer treatments that are toxic to cancer cells. Unfortunately, these same treatments may also be toxic to other living cells, such as bone marrow cells, hair follicles and the cells of the gastrointestinal tract. Conventional veterinary cancer care seeks a successful balance of cytotoxicity between cancer cells and healthy cells in the body. Drugs, radiation, and even some supplements can be cytotoxic in the body. This word implies that the cells would not have died without the use of the agent or treatment.

Decompensation
: When a dog can no longer hide or mask the signs and symptoms of disease and suddenly becomes very obviously sick. Dogs have a talent and instinct for compensation, or hiding their symptoms, which is why they can seem to get sick “overnight” when they finally decompensate.

Dirty Margins
: A biopsy is said to have dirty margins when the pathologist sees tumor cells in the margins of normal tissue examined during the
comprehensive margin evaluation
. Dirty margins indicate that cancer cells are likely still in the body around the surgical incision or scar.

Double-blind, Placebo-Controlled Study
: The preferred way that conventional medicine evaluates treatments. In this type of study, at least two groups of identical (or as near as possible) patients are given treatments. One group receives the actual treatment being studied (the treatment group) and the other does not (the placebo group). Neither the doctor nor the patient knows which group is getting which treatment (double-blind). The treatment is evaluated by comparing its effectiveness with the placebo. While this can be useful, it is not the only way to thoroughly and thoughtfully evaluate a treatment. Using only treatments “proven” by this kind of study excludes many that may be just as – or more – effective. There are treatments proven by historical use, from other systems, or even those that may be untried, but worth a shot in a last-ditch effort to treat the dog. Other countries, including Japan and several European countries, rely more on historical use and the experience of practitioners. Some researchers consider the use of placebos to be cruel, and instead choose to compare a group of patients receiving the new treatment to a group of patients receiving the current best treatment. While some clinical researchers in American western medicine are using this approach, most scientists still feel the double-blind, placebo-controlled experiment is the gold standard.

DNA
: Deoxyribonucleic acid (DNA) is a chain of molecules that contains the genetic instructions for any living organism. DNA is like a blueprint, a recipe, or a code. It stores information about how the body will develop and function throughout its life. DNA has segments, called
genes
, which carry this genetic information and help cells develop, live, and die, all according to the instructions in the DNA.

Durable Remission
: This diagnosis is achieved when there are no measurable signs of cancer, and there have been no signs for a reasonable length of time. Most oncologists consider a remission durable after fourteen to twenty-one days. If a patient cannot stay in remission between treatments, it is typically not an effective treatment.

Fine Needle Aspirate
: This is an initial screening procedure which vets use to test a tumor or other site in the body for malignant cells. A skinny needle is inserted into the site, which draws up a small sample of the cells and fluids inside the tumor. The sample can – in many cases – confirm the presence and type of cancer. Fine needle aspirates cannot be used to grade a cancer, and their results can sometimes be inconclusive. This type of aspirate can also be used to sample lymph nodes, the liver, the spleen, the kidney, or other sites. This procedure typically does not require sedation or anesthesia and is often relatively inexpensive.

Full Spectrum
: This is my phrase to describe an unbiased, results-oriented, strategic approach to cancer care. The goal is to optimize life quality and increase longevity. As a Full Spectrum vet, I consider and treat all aspects of cancer, including diet, lifestyle, and the psychological well-being of both the patient and the guardian. Conventional tools (chemotherapy, surgery and radiation) are part of Full Spectrum cancer care, as are many alternative treatments and others, never previously considered for canine cancer care.

Gained Life Expectancy
: How long do we expect a dog to live if he does not get treatment for his cancer? How long do we expect him to live if he does? The difference between those two numbers is the gained life expectancy of that treatment. For example, if we expect that a dog has two months to live, but with treatment could live six months, the gained life expectancy is four months. Knowing the gained life expectancy can be helpful when making treatment plan choices.

Genes
: Genes are segments of DNA, which carry codes for specific proteins, functions, and cell processes in the living organism. A gene usually contributes to the control of a small segment of what happens in a cell or in a body. Altogether, genes manage every facet of life on the tissue, organ and body level. Genes behave like microscopic cell managers, while making sure that everything happens according to their instructions.

Grade
: How aggressive a cancer is can be predicted by its grade. To grade cancer, a pathologist examines a biopsied tumor under a high power microscope and notes special characteristics of the cancer cells, which can indicate how aggressively they may behave in future. Sometimes, veterinarians and oncologists use words such as “angry” or “hot,” to describe very aggressive tumors. Different grading systems are used for different tumor types, but generally the more aggressive a tumor is the higher is the number assigned. “High grade” tumors are more aggressive and “low grade” tumors are less so.

Historical Use
: This term suggests evaluating treatments by looking at their use over time, rather than using clinical studies. Some drugs, like aspirin (pain relief) and phenobarbital (anti-seizure), were used before the Food and Drug Administration (FDA) started regulating pharmaceuticals. These drugs, which have strong historical evidence of working in the body, are grandfathered into the system and do not need to go through the lengthy (ten to fifteen years) and extremely expensive (millions of dollars) approval process. Since 1938, new drugs undergo safety and efficacy trials to prove to the FDA that they work for the purpose for which they are intended. Drugs are usually approved for one, fairly narrow use, although their action may be useful in other diseases. Once approved, doctors and veterinarians can prescribe them for their approved purpose, or for any other purpose they judge to be safe and appropriate. A classic example of this is using phenobarbital – grandfather-approved for seizures – as a sedative. This practice, called off-label prescription, is very common, especially in veterinary medicine. Using off-label prescriptions, vets can prescribe a drug approved for humans for use in any other species. Vets may also use a drug approved for a condition in one species in a totally different species, and even for a different condition. There are two chemotherapy drugs approved for use specifically in dogs; both are approved for some types of mast cell tumors: Palladia and Kinavet CA-1. Many, but not all, other chemotherapy treatments used in conventional care have been reviewed for safety and efficacy in dogs, but do not have specific FDA approval. If a treatment (drug or not) has been in use for a long time and is successful, it is considered valid, even if there are no FDA studies “proving” its validity. Most pragmatic vets agree with this point of view, although a few demand more proof.

Homeopathy
: An alternative medical practice started in Germany in the late eighteenth century, homeopathy uses extremely diluted substances to stimulate symptoms similar to what the patient is already experiencing, according to the principle of “like cures like.” For example, if the patient is coughing, a remedy might be given that would cause coughing in a healthy person. Despite this counter-intuitive reasoning, homeopathy has been shown to be useful for certain forms of brain cancer, in combination with drugs. It may also be useful for other cancers. I recommend consulting with a veterinarian trained in homeopathy, if you are interested in using it.

Immune System
: The body’s defense against external microbes and viruses, and also the body’s “cleanup crew” for deranged and mutated cells. Incredibly complex, it can be strengthened or weakened by nutrition, emotional states, sleep (or lack of it) and stress. A strong immune system deploys cancer-fighting cells to destroy cancer, but if cancer overwhelms the system (which it can), immunity is suppressed. This creates a higher risk for secondary infections. There is even evidence that cancer can recruit certain immune cells to help the cancer spread or metastasize. For more details on how the immune system operates, see the vaccination discussion on
page 87
. Strategic boosting of the immune system is an important part of Full Spectrum cancer care.

In Vitro
: Means “in glass” and often refers to a treatment that is tested in a test tube, a petri dish, or in other equipment in a lab. Many promising cancer therapies work very well
in vitro
, but not
in vivo
.