Medical jargon can be confusing and I know I easily fall into the trap of using terms whose definition may not be intuitive to a non-medically trained person.
Here are some basic definitions of the more common oncology terms as a resource for owners who may be puzzled by the words we use on a daily basis.
Typically we obtain cytology samples when we perform what are known as fine needle aspirates. Fine needle aspirates are when we introduce a small needle (generally the same size as used to administer a vaccine or draw a blood sample) into a tumor and then try and extract cells. The material is usually dispersed on to a slide, and generally always submitted for analysis by a clinical pathologist.
Fine needle aspirates are quick, relatively non-invasive tests we do routinely as a means to obtain rapid results as to the cause of a tumor or to investigate whether an organ or structure is showing evidence of tumor spread. The major con to cytology is the samples obtained are usually small, and may not represent the entire tumor, so it’s possible to have a non-diagnostic sample, or even completely miss a diagnosis of cancer.
Biopsy samples are obtained in two main ways: incisional biopsy or excisional biopsy.
Incisional biopsies are when small pieces of tissue are removed from a larger tumor, with the intent to try and characterize the mass prior to more definitive treatment.
Excisional biopsies involve the removal of the entire tumor, or affected organ or structure.
It is often more valuable to take an incisional biopsy first, even if this means two separate anesthesia or sedation procedures, and slightly increased cost. This is because a great deal of information can be obtained from an incisional biopsy that is used to plan the more definitive surgery.
Several studies have proven performing a pre-treatment incisional biopsy is beneficial for outcome for pets. Biopsies, therefore, are considered the “gold standard” diagnostic tool for most cancers.
Stage refers to where in the body to we find evidence of cancer. Most human tumor types have specific staging schemes, and we have applied these same outlines to our veterinary patients. In order to assign a particular stage to a tumor, the pet would have to undergo all of the required staging tests.
For example, dogs with lymphoma can be assigned to one of five possible stages, but only if all the required tests are performed, including labwork, imaging tests of the chest and abdomen, bone marrow sampling, and lymph node biopsy with immunophenotyping. The stage of cancer is important because it can dictate treatment options, prognosis, and also allows owners and veterinarians to literally know everything about the pets from nose to tail.
Grade is a specific term used to describe biopsy features related to a tumor. Grade can only be determined when a biopsy has been performed on a tumor. This means grade cannot be determined via cytology samples.
Tumors are typically designed as either high-grade or low-grade. Not all tumors have a specific grading scheme, but for those that do, it’s very important the pathologist assign a grade when they write a biopsy report. This information is one of the main features I will use to make therapeutic recommendations.
Aggressive is a term used by oncologists to describe tumors that are either 1) extremely difficult to remove surgically, 2) highly likely to spread throughout the body, or 3) both.
You may think this term would apply to all cancers, but we do know that some tumors, or subtypes of tumors, do not behave aggressively if diagnosed early or found at an early stage.
Remission typically refers to a description of cancer where we know it still exists in the pet’s body, but all the cancer cells are below the level we can detect it with any available test. Remission does not equal cure, but still represents successful treatment because the disease burden in the animal’s body is reduced well below the level at which we would expect to cause illness or signs. We usually refer to remission when we describe the treatment of blood-borne cancers, such as lymphoma, leukemia, mast cell tumors, histiocytic tumors, etc.
Median Survival Time
The median survival time is usually the best measure I can give owners when they ask me how long their pet is expected to live with or without a particular treatment. Median typically refers to “the middle”, so when we talk about this statistic we usually mean 50% of pets live shorter than that number and 50% live longer. It’s not technically the same thing as an “average” survival time, as the median survival places less emphasis on the “outliers” – pets who succumb very quickly or live a very long time after diagnosis.
Of course, we always hope the outcome will be more favorable than the “average”, as generally there is nothing average about any of our patients!
As morbid as it may sound, I consider an animal cured of their cancer should they pass away from a process other than their tumor, and at the time they pass away, their tumor can no longer be detected in their body. I often use the word “control” rather than “cure” when speaking to owners as I feel it better delineates my goal in treating their pet. I wish to make their pet’s cancer something they live with more as a chronic, but non-debilitating, condition.
I’m aware of how confusing and scary a diagnosis of cancer can be and rest assured; we are here to make this whole process a little less intimidating. I would rather be asked the same question repeatedly than feel as though an owner left not understanding what was happening to their pet.
The words may be unfamiliar, but I guarantee you, we are all speaking the same language. Except usually one of us is just wearing a fancier white coat.
Dr. Joanne Intile