Because we know and understand how hard it can be to have a pet with cancer, we try to focus our conversations on your questions and the most important facts of your pet’s cancer. Sometimes, we accidently let an oncology word or two slip into the conversation. We don’t mean to do this, but these are the scientific words we pet cancer vets use every day to communicate with each other. So we thought an “onco-speak” translation guide below may be of help.
What Your Vet Says — and What They Mean
Sarcoma/carcinoma/round cell tumour:
Oncologists group tumours into three main “families”: sarcoma, carcinoma and round cell tumours. This is based on how the tumour cells appear when we look at them under the microscope. Sarcoma cells appear elongated or spindle-like, carcinoma cells form clusters, groups or sheets, and round cells are… well, round. Most times a tumour has a specific name such as a thyroid carcinoma. Other times, the tumour cells are so abnormal we can only say it comes from one of the three families and need to perform additional testing to determine its origin. Knowing the origin helps us to treat it appropriately.
Median survival time:
We know that what you most want to know is how long your pet will live, but we can only give you information based on large groups of pets with similar tumours and treatments. “Median” is a statistical term used in scientific publications to communicate how long pets with a certain tumour live when treated with a particular protocol. Median represents the midpoint of the data. So, if we say the median survival time for pets with cancer X is 12 months, we don’t mean your pet will die exactly 12 months from now. What we mean is that 50 percent of pets with this type of cancer will live more than 12 months while, sadly, 50 percent will live less than that amount of time. It can be hard for us to project what an individual pet’s survival time is likely to be.
According to the dictionary, prognostic mean is predicting the future or forecasting. Like the weatherman, oncologists are pretty good at anticipating what the likely outcome for your pet will be, but sometimes the tumour does not follow the rules and we can be way off base. A “prognostic factor” is something about your pet’s tumour which positively or negatively influences how well your pet will respond to treatment. Read the next two definitions, grade and stage, to understand two common prognostic factors.
If your pet has cancer, they may have a specialist, called a veterinary pathologist, involved in their diagnosis and care. You may never meet this specialist, but veterinary oncologists depend on pathologists to look at tumour biopsies under the microscope and to determine the type of tumour. For many tumours, they also “grade” the specimen. Grade is commonly determined by the number of dividing tumour cells seen in the biopsy, the degree of abnormal structures the cancer cells show, and if the tumour cells demonstrate invasion into blood vessels or underlying body structures. A higher grade typically confers a worse prognosis and spurs your pet’s oncologist to recommend more treatment. For example, a grade I mast cell tumour is typically cured by surgery alone, but a grade III tumour may need chemotherapy and radiation treatment.
To determine the stage of your pet’s tumour, we evaluate the entire pet using physical examination, blood tests, x-rays, ultrasound or advanced imaging such as CT scan and MRI. Stage is an example of when bigger is not better since the more tumour we find, the higher the stage. In all tumours, the highest stage is given when the tumour has spread widely throughout the body. A tumour with a high stage carries a worse prognosis.
This is a harsh word and is easily misconstrued. When it is used to describe a tumour, it means the tumour is likely to spread rapidly or recur quickly despite treatment. When it is used to describe a treatment, though, it can unnecessarily strike fear in the heart of the pet owner due to concerns about unbearable side effects. So instead of using “aggressive” to describe a treatment, we prefer to say that this option has the best chance of controlling your pet’s tumour long-term and then we describe the expected reaction. Discussing treatment in these terms can usually help avoid evoking an emotional response.
Defining this term may be unnecessary. These are the two words every pet owner wants to hear from their veterinarian. “Complete remission,” sometimes also called no evidence of disease, means we cannot find any clinical evidence of the tumour in your pet. This diagnosis is typically based on physical examination, blood tests, x-rays and ultrasound or advanced imaging such as CT scan and MRI. If you and your pet are lucky, the tumour will stay away forever.
We hope if your pet has cancer, you get to hear these words soon. Keep in mind: Not all cancers in pets are fatal and that your pet’s diagnosis may still come with a happy ending.