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 cancersbreast, brain, and especially boneare 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 pets 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, its all about the emotional value one places on ones 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 cancers impact on people. And while not every pet owner can or will choose to treat an animals 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 theyll get, and its 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, Penns 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, Penns 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 dont 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 pets 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, Bentleys 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 Bentleys 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 animals 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 dont 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 C86 in the November/ December issue.
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