The Dog Cancer Survival Guide by Susan Ettinger Demian Dressler Page B

viruses, bacteria, and other invaders so that white blood cells can destroy and dispose of them), the stations. Because the lymphatics reach nearly every organ, cancers that occur in the lymph cells – lymphomas – are by definition systemic cancers . Other types of cancer may also use the lymph system as a means to metastasize . For this reason, lymph nodes are often aspirated or biopsied during cancer diagnosis, to check for spread.
    Malignant : A tumor, which is dangerous and growing uncontrollably, is called malignant. This word is a synonym for cancerous. Another word used to refer to a malignant tumor or a cancer is malignancy.
    Margin : This refers to the area of normal-seeming tissue surrounding a tumor that has been removed during a biopsy or other surgery. This area may contain microscopic cancer cells, so, a pathologist examines it during a comprehensive margin evaluation . If the margins are narrow (one or two millimeters), malignant tumors are more likely to recur. For this reason, wide margins of two to three centimeters are preferred.
    Maximum Tolerated Dose : In conventional treatment, this phrase is used to describe the highest dose of chemotherapy that can be given without the patient’s having unacceptable, severe side effects or dying from the treatment. The higher the chemotherapy dose is the more cancer cells are killed; therefore, the aim of chemotherapy is to give as high a dose as possible with the fewest (manageable) side effects. There is a great deal of information on chemotherapy side effects and how to manage them in Chapter 11 .
    Measurable Disease : This refers to a tumor that can be measured for size with calipers or imaging techniques; also called macroscopic disease. You can see these tumors with the eye, unlike microscopic tumors, which are too small to see without magnification.
    Median Survival Time : The time, from either diagnosis or treatment, at which no more than half of the patients with a given cancer are expected to be alive. For example, if a group of dogs all have lymphoma and all start the conventional chemotherapy protocol that Dr. Ettinger recommends, she would expect half of those dogs to be alive after fourteen months, and half of them to have passed. It is useful for the guardian to know this number, but it is also important to remember that it is only a guide. It does not apply directly to any particular dog. Some vets use the term “median overall survival” or the term “median survival.”
    Metastasis : When cancer spreads to distant sites in the body by slipping tumor cells into the circulatory system (the blood or the lymph), we call it metastasis.
    Metronomic Chemotherapy : A relatively new approach to chemotherapy, which doesn’t attempt to kill cancer cells directly (like maximum tolerated dose does), but instead attempts to cut them off from their supply of oxygen and nutrition. Low doses of drugs are given on a regular basis to target the lining of the blood vessels feeding the tumor. This can stop the tumor from building new blood vessels ( angiogenesis ). Some tumors may stop growing, while others may shrink. The low doses mean that the normal tissues of the body are rarely affected, and side effects greatly reduced. See page 137 for more details.
    Micrometastasis : This is the spread of very small numbers of cancer cells to distant sites through the circulatory system. Micrometastasis is usually undetectable (or undetectable with our current diagnostic tools), due to the small numbers of cells that have spread when the diagnostic tool is applied
    MRI : MRI stands for magnetic resonance imaging, which is an imaging technique that uses powerful magnets to generate electromagnetic fields. These fields pick up information in the body and broadcast it to a radio antenna. The resulting image is a series of “slices” much like what is seen in a CT scan, with much more detail. MRI is an advanced imaging device and is typically only available in very large