What Happens When Pets' Cancer is Not Treated?

“And what happens if we don’t do anything?”

This is a natural question to ask when presented with an abundance of treatment options for a pet that has been recently diagnosed with cancer.

In order to make the most informed decision about what is the correct choice for their companion, it’s easy to understand how, regardless of tumor type, owners need to know the theoretical choices designed to help their pet live a longer life, and the alternative of what might happen if no further therapy is pursued.

I can absolutely appreciate why an owner would want to know about the “what if we do nothing” option and I’m surprised if it doesn't come up at some point during a consultation. Of course, there are some owners who simply want to do everything possible for their pets, trusting in my opinion and/or experience. In many of these cases, I often find I am recommending chemotherapy protocols on a theoretical basis rather than evidence based information and it’s almost as if we are embarking on a voyage into the unknown.

Truthfully, as alluded to in last week’s column, it’s very difficult for me to predict what the outcome might be for dogs and cats that don’t undergo treatment. Few veterinary studies focus on what happens to untreated cases, and those that do are often limited in follow-up information, so conclusions are somewhat unclear.

Studies are generally designed to focus on a therapeutic plan designed to extend an expected lifespan or to time the progression of the disease. These parameters are often reported in terms of absolute time durations rather than comparing the outcome for treated pets with the outcome for untreated pets. Ideally, studies would include a control group of patients receiving a placebo treatment, or at minimum, a group of pets not receiving further therapy, with a long-enough follow-up time for the untreated group for results to be meaningful. Since most studies lack adequate control groups, it’s often difficult to know if a treatment truly affords a benefit.

There are certain instances where I discuss the possibility of close careful monitoring in lieu of pursuing treatment. This typically consists of recommending monthly physical exams and periodic labwork, and imaging tests to examine for recurrence and/or spread of the disease. Despite my recommendation, it’s uncommon for owners to pursue strictly observational exams with me, which also makes it difficult for me to know what happens in cases where definitive treatment is not pursued.

When owners do elect to pursue diligent monitoring with me directly, I’m extremely appreciative of their efforts and trust in my care. I’m always honest with owners. I let them know I haven’t been a veterinary oncologist forever, and that despite the fact that I may lack the dozens of years of experience some of my colleagues have, I’m always willing to continue to expand my knowledge base. Even when pets are just being monitored with their disease, I can stand to learn a great deal from their status.

Even when I do have untreated pets to follow-up with me, since I’ve changed my location of where I’ve worked as a veterinary oncologist three times over the span of less than seven years, I’ve not been located in one geographical area for consistently long enough to have adequate long-term follow up on these cases. But I do believe there is something to be learned from every patient who walks through our hospital’s doors, and I really value the opportunity to be a part of their care, whether definitive, palliative, or simply just carefully watching them over time.

I often tell owners that their best resource for guiding them through what will happen if they don’t elect to pursue additional treatment is often their primary care veterinarian. They are often the individuals who have the most follow-up information on such cases and can provide more accurate information as to how things might transpire.

I also really appreciate when owners update me as to how their pet is doing weeks to months (or in rare cases, even years) after I’ve seen them as an initial appointment, though we haven’t proceeded with more definite treatment and I haven’t been the veterinarian examining them during the interim. I actually learn a great deal from such cases, and can use that information to help other owners make decisions about what is right for their pets when a similar situation arises in the future.

In other words, I never take it personally when an owner tells me, “You said Fluffy wouldn’t live past three months, and here we are ten months since surgery, and she’s doing great!”

And typically, neither do the owners.

Dr. Joanne Intile

Image: Annette Shaff / via Shutterstock

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