Penn’s veterinary hospital not only offers treatments that can prolong quality of life when a pet gets cancer, but also conducts research that sheds light on the disease in humans.
By Kathryn Levy Feldman | Illustration by Gina Triplett
My 20-year old son found the lumps. He had been playing with our Lassie look-alike, Bentley, when he felt two masses almost the size of tennis balls under his neck.
“Mom, you better take a look at this,” he called.
“Oh, they’re probably nothing—just another one of his skin infections,” I said lightly after my inspection of our dog, who was then seven years old. “I’ll call the vet just to be sure.”
Even as I dialed the phone, I knew in my gut that it was not good. At Bentley’s appointment later that week, our vet confirmed my worst suspicions.
“They feel like lymphoma,” she said in her characteristic no-nonsense style. “I think we should do a biopsy as soon as possible.” Almost as an afterthought, she added, “I’m sorry.”
So began our family’s roller coaster ride with canine cancer, a shaky journey, at best, on which, I soon discovered, we have a lot of company. Cancer is the leading cause of death for dogs, killing 26 percent, and it accounts for almost half of deaths each year in animals over the age of 10.
Those figures may be just the tip of the iceberg, according to Dr. Karin Sorenmo, section chief of the oncology department at Penn’s Matthew J. Ryan Veterinary Hospital. “We are seeing the same thing in veterinary medicine as we are in human medicine, that the incidence of certain cancers is increasing,” explains Sorenmo, who is also assistant professor of oncology at the School of Veterinary Medicine. “And since not all companion animals who are diagnosed with cancer receive treatment, we may, in fact, be underestimating the prevalence of the disease.” She estimates that the hospital’s oncology department had about 2,800 patient visits last year. “There is most definitely an increased demand for our services.”
There are numerous reasons for the cancer increase in dogs and cats, not the least of which is longevity. Like people, companion animals are living longer due to better nutrition, preventive medical care, and quality of life. The longer an animal lives, according to Sorenmo, the more likely it is to develop cancer. “Cancer is a disease of the aging.”
Sorenmo also speculates that perhaps 80 percent of all cancers are environmental. For example, studies have linked higher rates of cancer in dogs and cats with sharing a home with smokers. Certain types of commercial lawn care are associated with an increased risk for lymphoma in dogs and cats, just as the use of certain herbicides and pesticides has been linked to a similar risk in humans who are farmers, Sorenmo notes. “We also see more bladder tumors in animals that live in or near swamps, and white cats that live outside are at greater risk for skin cancers,” as are dogs with white hair and thin skin.
Researchers have also discovered that certain breeds of dogs are more susceptible to the disease than others. In a 2001 study at Penn’s veterinary hospital, 56 percent of all golden retrievers and 52 percent of all boxers who died there were found to have died from cancer. “Cancer is more common in golden retrievers than in any other type of dog,” Sorenmo reports. “Whether this is true because golden retrievers are an extremely popular breed and there are simply more of them, we don’t know.”
Other breeds with a notably high incidence of cancer include Rottweilers, Bernese mountain dogs, Boston terriers, English bulldogs, Scottish terriers and Cocker spaniels. Bentley’s breed, collies, have a relatively low incidence of cancer. All of which proves that you never know.
Like us, most pet owners first learn of their animal’s cancer in their local veterinarian’s office. In the initial stages of the disease, most animals don’t seem sick and many tumors are detected as part of routine examinations. The next step is an accurate diagnosis, which usually involves a biopsy.
In Bentley’s case, our vet removed a lymph node from his hind haunch and sent it to the lab. When the result indicated lymphosarcoma, she referred us to Ryan Hospital’s oncology department for staging and treatment. By the time we got Bentley to Penn (about a week after his biopsy), he had developed a significant bacterial infection at the incision site (which was swollen and oozing, despite oral antibiotics) and was very weak and lethargic. He was barely eating (grilled hamburger and bacon seemed to be the only things we could get him to swallow, and they wreaked havoc on his digestive system), and he could hardly jump into the car. I was convinced that he wasn’t going to be with us for much longer and my heart ached for this beautiful, gentle animal that was trying so hard to maintain his dignified composure.
Ironically, while cancer may be the leading cause of death in geriatric dogs, it is also the most treatable disease, when compared with congestive heart failure, renal failure, and diabetes mellitus. Which was probably why our oncologist, Dr. Beth Overley, was optimistic about Bentley’s prognosis. Lymphosarcoma, a cancer of the lymphocytes (a type of blood cell), and lymphoid tissues, is the third most common cancer diagnosed in dogs and, as she put it, “is the best one to get.” And while Bentley was certainly sick, she wouldn’t know how sick he was until they performed a series of tests to search for tumors in other locations.
Given how enlarged his lymph nodes were, she recommended that we leave Bentley at the hospital for the rest of the day for “staging” and, pending the results, his first course of chemotherapy. Encouraged by the first optimistic news we had heard in a month, we left Bentley in what we knew were some of the most capable and compassionate hands we had ever encountered. As sick as he was, he wagged his tail and eagerly followed Dr. Overley as if he knew she might be able to help him.
“Staging helps us evaluate the stage of the disease and helps monitor its progression,” Sorenmo explains. “It can also help influence an owner’s decision to treat the animal. We know a lot about the biological behavior of tumors, and radiographs and ultrasounds of the lung and abdomen are extremely informative.” In addition to chest x-rays and an abdominal sonogram, Bentley would undergo a complete blood count, a serum chemistry profile and urinalysis as well as a bone marrow aspirate.
By the end of the day, we had the results. Bentley’s official diagnosis was stage Vb Lymphosarcoma. The cancer was present in his lymph nodes, some abdominal organs, and his bone marrow. The good news was that his chest x-ray did not show any evidence of either a mass or metastasis, but there was no denying that Bentley had advanced stage disease. He also had a significant infection at the site of his incision.
In spite of what sounded, to me, like a fairly bleak prognosis, Dr. Overley remained hopeful and encouraged us to treat our dog. Lymphosarcoma, she told me, is incredibly sensitive to chemotherapy, and up to 80 percent of dogs treated go into remission. The length of the remission will vary from pet to pet, but for those dogs that have the most common type (lymph-node enlargement), the average remission time is usually around 8-10 months with an overall survival time of about one year. From where Bentley was right now, one year sounded awfully good.
She explained that there were essentially two chemotherapy options, a long and a short protocol. The difference is the amount of time (1.5 years versus 22 weeks) and the toxicity of the treatment. The long protocol involves treating the animal once a week for 4-6 months, then restaging; if all is clean, the dog is treated every other week for another 4-6 months. If still clean, another treatment resumes every third week, for 4-6 months. At that point, if everything is still clean, the treatment is discontinued.
The short protocol uses two drugs per week for 22 weeks, and then stops. It involves less time and money, but it carries an increased risk of toxicity.
She told me that in her experience, side effects are seen in less than 5-7 percent of dogs and range from gastrointestinal disturbances to infection associated with a low white blood-cell count. In a recent Penn study examining owners’ impressions of their pets’ quality of life while undergoing chemotherapy, the dogs treated at Penn were given an 8 on a scale of 1-10, with 10 being the highest. Most owners claim that their dogs are the same as ever, and some even say they are better than they have ever been.
There was no way of knowing, of course, how Bentley would respond to the treatment, but the most common side effects include nausea and vomiting, both of which could be controlled with medication. Overley did not think he would lose his hair, although the growth might be slowed, and she recommended that we proceed immediately with the short protocol. By the time I picked Bentley up later that afternoon, he had already received his first chemo treatment.
Sporting a new “bikini cut” courtesy of the ultrasound, Bentley was delighted to see us and seemed none the worse for wear. I was sent home with what seemed like an entire pharmacy: two antibiotics for his infection, anti-nausea drugs in case we needed them, a steroid to be given for one month in gradually decreasing doses, and samples of dog food for cancer patients. “We have found that tumors don’t grow as quickly on a high-fat diet,” Overley explained as she went over my instructions for the week. She repeated her optimistic projections. “Usually we see a decrease in size in the lymph nodes within 24-48 hours,” she said, showing me how to palpate his glands. Promising to check in with us in a day, she sent us on our way.
Later that night, when I tentatively felt Bentley’s glands, they did indeed seem smaller to me, but I thought I was imagining things. The next morning they had all but disappeared. When Bentley eagerly gobbled down his new dog food, the first dog food he had eaten in weeks, I allowed myself to share some of Dr. Overley’s optimism. Maybe this wasn’t going to be so bad after all.
Bentley’s chemotherapy regime consisted of a four-week induction cycle, with one week of rest, repeated three times, followed by seven weeks of every-other week treatment. He made it through all 22 weeks with remarkably few side effects; in fact he seemed to feel better than he had felt in a long time. He had occasional gastrointestinal issues, which we controlled with medication; his hair did not completely grow in from his first ultrasound, and he lost some weight. But, looking at him, it was hard to believe he was actually sick. He was alert, playful, energetic, and actually seemed to love to go on our weekly outings to Penn, where they treated him like a visiting dignitary. Each treatment took about two hours, and I was able to drop him off and pick him up at my convenience.
Quality of life, a term I heard repeatedly during Bentley’s sojourn at Ryan Veterinary Hospital, is the mantra of the oncology practice. While the three standard treatments for cancer in humans—surgery, radiation therapy, and chemotherapy—have been adapted successfully to help animals with cancer, the goal of treating cancer in the veterinary patient is to prolong good quality of life for as long as possible, not to cure the disease. Dr. Lili Duda, radiation oncologist at Ryan and editor of the veterinary section of Penn’s OncoLink website (http://www.oncolink.com), puts it this way: “We’re not willing to undertake an aggressive treatment that might cure half of our patients if it is very likely that it will make the other half suffer from serious and even fatal complications.” To that end, treatment in animals is typically less aggressive than in humans, where the usual goal is curing the cancer.
While the treatment goals may differ, Duda and her colleague, Dr. Stephen Withrow, chief of clinical oncology at the veterinary school at Colorado State University and co-author of the textbook, Small Animal Clinical Oncology, are clear that the nature of the disease is the same. “Cancer is cancer,” regardless of whether it develops in an animal or a person, says Withrow, whose own work on dogs with osteosarcoma has contributed to improved treatments for humans with the disease. Approximately 80 percent of animal cancers—breast, brain, and especially bone—are a “direct correlate” to human cancers. To that end, any work in the oncology field, whether focused on animals or humans, is important in advancing our knowledge of the disease.
Ironically, the current scientific model calls for anti-cancer agents to be tested in laboratory rats or mice in which researchers induce cancer. A better model, argues Duda, is to study naturally occurring cancers in cats and dogs. “These cancers better mimic what happens in people,” Duda continues. “Pets live in our homes and share their environment with humans.” In addition, companion animals are more similar to humans physiologically than rodents.
According to Duda, companion animals are also a useful model because cancer progresses much more quickly in animals, making clinical trial data available much faster. “You might have to follow a child for 20 years after a trial to see if the cancer recurs,” says Duda. “But you would know this within a few years with an animal.”
The study of cancer in companion animals and humans is a promising and relatively new field called parallel research, or comparative oncology. Cancers of the throat and mouth, routinely treated in veterinary hospitals, may hold the key to understanding human oral cancer. Duda, among others, would like to see more clinical trials in which the most promising treatment approaches for cancer are used in companion animals first, instead of the other way around. Photodynamic therapy, which involves using a drug to make a tumor sensitive to light and then exposing it to laser light, is being used to treat skin cancers in cats at the University of California, Davis, Center for Companion Animal Health as well as prostrate cancer in dogs at Penn.
Whether or not to treat a pet with cancer is very often an emotional as well as a financial decision. Sorenmo estimates the cost of a standard cancer treatment in a companion animal to be between $2,500 and $3,000. Even she admits that few cases are “standard.” Osteosarcoma treatment, which often requires amputation, can cost between $4,000 and $5,000, yet this procedure will double your pet’s chances of survival. “People do it,” she says. “We see very select clients here who are willing, able, and ready to treat their pets. To a certain extent, it’s all about the emotional value one places on one’s pets.”
Numerous studies have shown that the emotional bond between human and animal is just as real as the bond between humans. “Pets are surrogate family members for many people,” especially for those who are widowed or live away from family and friends, Duda says. “The mental anguish and anxiety experienced by owners of pets with cancer are an undeniable part of cancer’s impact on people.” And while not every pet owner can or will choose to treat an animal’s cancer, having that choice is important, she argues.
But treatment decisions are still agonizing. Kathleen Dunn, chief social worker at Ryan, is on call at all times to counsel owners coping with emotional issues surrounding their pets. She runs a support group for grieving owners that meets every two weeks and counsels those who bring in their seriously ill animals for treatments. Mostly, she admits, she listens. “All the owners think their pet is the most wonderful in the world,” she says. “They have high expectations of the care they’ll get, and it’s inspirational to see the care the animals get from the staff.”
Ultimately, however, it often comes down to the quality of life issue. If the goal is to cure or control the cancer, then some owners may be willing to tolerate treatment side effects with a higher risk, severity, or duration. “Several days or weeks of decreased quality seem reasonable in exchange for many months of good quality of life,” Sorenmo says.
If, however, the cancer is incurable, then the goal of the treatment becomes palliative, which is an attempt to maintain or improve quality of life without attempting to prolong life. Duda treats a fair number of patients with palliative radiation therapy, or what she calls “comfort care.” “Radiation is very effective in alleviating symptoms of tumors, such as bone pain,” she explains. “About two-thirds of patients have moderate to significant improvement, and the effects can last for a few weeks to several months.”
Radiation is also used to treat localized disease in its early stages, typically following surgery, when there are tumor cells remaining, or even before surgery to shrink tumor size. In some cases, radiation therapy can offer permanent control of a tumor.
Although radiation oncology was not approved as a veterinary board specialty until 1994, Penn’s veterinary school had one of the first radiation-therapy units in the country, dating back to the turn of the century. “It was used primarily for large animals. Horses had economic value,” explains Duda. “Radiation in companion animals is a relatively new field.”
Unfortunately, Penn’s current radiation equipment dates back to the late 1960s and can cause unnecessary side effects. The Vet School has launched a $100 million fundraising campaign (see article on page 18) to pay for several projects, including the conversion of the hospital garage into a state-of-the-art radiation therapy and imaging suite, including a linear accelerator, MRI, and scintigraphy equipment. “The new machines are less damaging to the skin of patients,” Duda says. “It is frustrating to lose patients to private facilities with better equipment but not necessarily board-certified practitioners.”
When all treatment options have been exhausted, Sorenmo and her staff feel strongly that their primary responsibility is to the animal. “In most cases, clients don’t want to stop treatment, even when we tell them there is very little else we can do, ” Sorenmo says. “They feel as long as we treat the animal, there is hope, and 10 percent is better than nothing.” However, just because a treatment is technically possible does not mean that it is the best thing for the patient. “Just as we have intervened in the pet’s life by providing aggressive medical care in an effort to improve and prolong quality of life, we intervene when these methods are no longer effective so that we do not prolong needless suffering,” she says. “It is the last act of kindness we can offer.”
Bentley completed his chemotherapy in January 2003, at which time he underwent a complete restaging. The results were dramatic: his blood work, x-rays, ultrasound, and bone marrow aspirate were all normal. On January 23, he was discharged from the hospital with a clean bill of health. My instructions were to have a monthly check up at my local vet and return in three months for reevaluation. A trio of oncologists brought Bentley to me with the good news, and I hugged them all. I drove home that afternoon with tears running down my cheeks and a panting companion in the back seat, thankful for the seeming miracle that had occurred on 39th Street.
Unfortunately, Bentley’s cancer came back with a vengeance six weeks after his discharge. We returned to Penn for the rescue chemotherapy protocol, but his immune system was too weak. Bentley died of cardiac arrest, brought on by bacterial pneumonia, in the ICU at the Ryan Veterinary Hospital on March 21, 2003.
My family misses our noble and dignified companion terribly. We have since bought a collie puppy, Amos, as well as pet insurance. As my daughter says, “A puppy cures all.” Well, not all, but a lot.
There is no doubt that Bentley’s cancer treatment affected the entire family. It was expensive, and at times exhausting and overwhelming. (It is a tremendous amount of responsibility to adhere to a chemotherapy regime for your pet as well as to interpret your animal’s reaction to the treatment.) At the same time it was incredibly rewarding. We were fortunate that Bentley responded so well to the treatment, and I know we gave him an extra six months of life in which he was relatively symptom-free. Did we just prolong the inevitable? Perhaps, but we also gave him a fighting chance to beat the cancer. Would I do it again, if given the same circumstances? Absolutely. I just hope I don’t have to.
Kathryn Levy Feldman is a freelance writer and a Penn parent. Her most recent article for the Gazette was on National Constitution Center President Joe Torsella C’86 in the November/ December issue.
