Well, I knew it would be difficult...
Occasionally, I have received e-mails from a dog owners asking me for information on cancer in the dog. Sometimes, knowing that I work in cancer research, some would indicate surprise that I had never written any articles for my web site on this specific topic. I could offer the excuse that it's because I work and write about cancer on such a regular basis that writing an article on this topic for my web site, my hobby, would be too much like work. But that wouldn't really be the reason why I've avoided this topic for an article. The truth is that I was afraid that I would be too tempted to cover every aspect of the disease. There is such an astounding amount of information on the subject of cancer and, like advancements in computer technology, new information is becoming available even as I type this sentence. And, as I feared, I want to include as much information in this article as possible, knowing, however, that I will probably later go back and say to myself, "I should have also included this...". As a result, I've decided to break up the article into parts. Also, I realized that there was no conceivable way I was going to finish this article by the September deadline I had set for myself. Therefore, I apologize for the delay, but once completed, I am hoping that the article will provide a thorough explanation of many aspects of the disease known as cancer.
Interestingly, a recent survey conducted of parents showed that other than fear of violence to their child, fear that their child would develop cancer was one of the top concerns of parents in the United States. I mention this because although this article addresses cancer in the dog, I am sure that I am not the only individual in society who puts my dogs close to, if not at the same level as I put my children in terms of nurturing them, protecting them and worrying about them. I think I can safely say that I am not the only one who will waste not a minute of time to demand a doctor's appointment for one of my children or one of my dogs if they show the slightest indication of illness. Yet, for myself, I commonly take the "I don't need the doctor, I'll feel better by next week" approach. It's a parental "thing", and whether a person is a parent of a two- or four-legged child, the protective instinct to preserve the well-being of those who depend on us for their survival is very strong.
Cancer poses a very real threat to both humans and animals: someone that you know either has cancer or will develop cancer within his/her lifetime, and one out of every five people will develop some form of cancer. Although these are very frightening realizations, the observation that more people are developing cancer now than in previous history is often misinterpreted as meaning that there are more cancer-causing agents in our present environment. Because age is a factor predisposing to cancer and people are living longer in current society, increase in cancer cases simply reflects an increase in the geriatric population. Another myth is that people are developing cancer at a younger age. The truth is that early detection programs and better methods of diagnosis are leading clinicians to identify afflicted patients earlier than what would have been possible years ago. These observations can also be applied to veterinary oncology: due to pet-owner education and disease-prevention in the form of proper nutrition, vaccination, heartworm prevention, etc. our canine companions are living longer, healthier lives which, ironically, puts them at higher risk to age-related cancers.
Invariably, when a new acquaintance discovers that I am a researcher in the field of oncology, the most frequent question I am asked is, "Will we ever find a cure?" My answer to that question is, "We have a cure." Even the polite acquaintance usually looks at me like I'm daft, the straight-forward acquaintance will pointedly inquire, "Then why do you still have a job?"
The major issue confronting our society today in regard to cancer is not finding a cure. When malignant disease is discovered in the early, localized stage it is 100% curable by either surgery or radiation and chemotherapy. The problem is improving our methods of diagnosis so that cancer can be discovered in this curable stage. Unfortunately, by the time many cancers are detected, even with current advances in diagnostic imaging using computer axial tomography (CT scan), magnetic resonance imaging (MRI), mammography, untrasound, and x-ray, most malignant cancers have already metastasized to distant, sometimes undetectable areas of the body which will complicate treatment and often prevent complete cure. Therefore, those of us researching cancer today are working toward the goal of improving methods of diagnosis for early detection of cancer or searching for treatments to prolong life and provide better quality-of-life in individuals with advanced, incurable disease.
In light of this, whether involving our children, our pets, our family and friends, or even ourselves, the significance of early detection in the cure of cancer cannot be stressed enough. Unfortunately, the act of relying on symptoms alone to indicate disease is not sufficient since by the time symptoms do present, many cancers have already spread (metastasized). Unfortunately, however, routine screening of both human and animal patients for the purpose of early detection is cost-prohibitive. Therefore, in human medicine, programs have been established to identify and educate individuals who may have a higher risk for developing certain cancers. It is important to remember, however, that absence of genetic predisposition should not lull an individual into false-security. That is, presence of a family preponderance for cancer does increase a person's risk that they may also develop cancer, but absence of cancer in the family does not assure freedom of risk. As pointed out in the accompanying article, there are many factors, of which genetics are only one, that contribute to the development of this disease. These factors play a pivotal role in the development and progression of both human and animal cancers.
Perhaps another common dilemma facing parents and pet-owners alike is the question of cancer treatment and its effects on quality-of life. When an adult is diagnosed with cancer, he or she is in most instances, capable of making an informed decision on whether or not to obtain treatment and endure the possible side-effects associated with such treatment. Though making the decision is not always easy, at least the choice is left to that individual. In the case of children, the decision of whether or not to treat is not usually a topic of debate unless the child is in an advanced or recurrent stage where prior therapy has failed. However, pet-owners are not bound by medical ethics to treat their pet for cancer. Therefore, when a pet-owner must decide on a course of treatment, there may be an added burden of guilt especially in cases where therapeutic gain may not outweigh the risks associated with treatment...then the question of whether to treat or not to treat, to continue treatment or stop treatment, or to pursue more radical approaches of treatment all become agonizing decisions. Because of the guilt factor, some owners may be compelled to go to the limits of therapy even when it is clear that the disease has progressed too far for therapeutic intervention. In contrast, some owners may immediately select euthanasia even before the disease begins to compromise the dog's quality of life. There is no easy formula for resolving such an issue as when to treat and when not to treat. Some clinicians use statistics related to therapeutic outcome to determine whether or not a patient (human or dog) should undergo treatment. However, in my opinion as a researcher, I do not believe statistics have a place in the decision of whether or not to treat an individual patient. This is because statistics make the assumption that all cancers treated with a particular regimen will respond in the same way, and we know that this is not the case. The cancers of no two individuals are the same. Each cancer develops from a single cell of that individual. Since genetic make-up of an individual's cells are unique to that individual, it is impossible to predict, based on the behavior of another individual's cancer, how a second person's or animal's cancer will behave. Therefore, as expected, even in clinical trials of treatments shown to have no significant efficacy against cancer, some patients may have partial or complete responses to that particular treatment, even though, as a group, no therapeutic gain can be reported. One cannot tell me that treatment did not make a difference to those few patients who did respond to therapy. Therefore, it is my belief that statistics should only be considered when trying to choose which therapy may provide the greatest likelihood of success rather than the means to judge an all-or-nothing approach to treatment.
Another issue which I often find to be a "hot topic" of debate among clinicians, researchers and the general public is the question of whether or not alternative medicine should be considered as a viable approach to cancer treatment. I believe beyond all doubt that a patient's state of mind plays an essential role in the successful treatment of that patient. This is clearly evident by the phenomenon of the "placebo-effect" in which, in many cases, patients who take sugar pills (or the like) while believing that they are actually taking a therapeutic drug demonstrate improvement of symptoms. Additionally, some of the drugs used in cancer today are derived from natural products of our environment and have a history as herbal and holistic remedies, albeit in a more crude form. It is probably unlikely, however, to expect a placebo-effect in dogs. Despite this, however, some owners have reported success for certain vitamins, herbs, and special diets in the treatment of their dogs with cancer. Therefore, though I do not believe alternative medicine should be used in place of conventional medicine, I do believe that it may have a place in conjunction with conventional medicine dependent on the owner's beliefs. As always, a major concern regarding the use of alternative medicines in dogs is possible side-effects of these remedies whose effects have not been explored in the dog. Therefore, as always, before administering any treatment, it is advisable to seek the advice of a veterinarian.
I guess this will conclude my personal remarks on this topic. It is my hope that, in its entirety, the information provided in the accompanying article may provide readers with a better understanding of cancer in the dog and insight into the latest techniques and therapies.
Copyright © 1999. Pamela A. Davol. All rights reserved. Copyright
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