Can dogs help us figure out cancer?
Two recent articles published in the journal Breast Cancer Research and Treatment suggest that man’s best friend could light the path towards fighting cancer.
A team of researchers from across Europe have found that canine breast cancer remarkably resembles human breast cancer, suggesting that treatments effective on dogs could be as beneficial to their owners.
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In the two related studies, researchers from France, Spain, Portugal, and Germany studied 350 dogs of various breeds with breast cancer. The first article details how factors used in human prognosis—tumor size, lymph node malignancy, kidney function, and other criteria—were applied to dogs with mastectomies, successfully predicting their survival rates.
The second study examines how chemical analysis, which is common in human diagnosis, applies to canine cancer cells. Researchers here discovered that more than three-fourths of those dogs developed an especially aggressive type of breast cancer for which there is currently no targeted treatment.
“Dogs are thus [useful test cases for] new therapeutic strategies for this particular subtype of breast cancer,” said Jerome Abadie of the Nantes-Atlantic College of Veterinary Medicine, Food Science, and Engineering, and primary author of the second article.
What Abadie and his colleagues are focused heavily on is understanding what canine tumors are like and in what ways they are similar to human tumors.
They’re also going to start clinical trials of new diagnostic techniques and therapies—early stage imaging, immunotherapy, and radiation therapy—on dogs, which could then be applied to humans. Abadie pointed out that cancer is the leading cause of death for dogs in the United States and Europe, meaning the pool of potential participants is large.
“The advantage is that the results of these trials, positive or negative, could be obtained in a shorter period of time in treated dogs compared to humans, as cancer in dogs evolves in months, compared to years in humans,” he told The Daily Beast.
That faster timeline could help doctors understand how cells mutate in human cancer and offer a glimpse into not only cancer treatment for humans, but for their good boys too.
The research is the latest in veterinary oncology, which has not only made strides in understanding animal disease but also leveraged that understanding for humans.
Unknown to many, veterinary oncology has been valuable to humans for decades. Bone marrow transplants, for example, are now a leading treatment for people with blood and bone cancers. But the approach was pioneered in the 1960s through tests on dogs, who develop these cancers 10 times more frequently than humans and exhibit them in very similar ways.
In fact, those similarities between canine and human cancer progressions have made dogs more attractive than lab rats or mice.
“Most experimental tumor models today involve studies on immune-deficient rodents,” Henrik Rönnberg, a veterinarian of three decades who is certified in oncology by the European College of Veterinary Internal Medicine, told The Daily Beast. “This may severely compromise the interpretation of results and the ability to translate the findings into humans with normal immune systems.”
Rönnberg said pets like dogs were advantageous because they not only have fully functional immune systems, but they develop spontaneous tumors, which are more complex than the malignancies induced in rodents.
Rönnberg recently joined AdvaVet, a company specializing in veterinary oncology, as its CEO. The newly launched company hopes to create new therapies for the estimated 12 million dogs and cats who develop cancer in the United States annually—80 percent of whom die within two years of their diagnosis due to the dearth of treatment options.
Those advances in veterinary oncology may save human lives as well.
“Aside from the advantages to pet owners who might be facing a cancer diagnosis in their cat or dog, humans who are seeking treatment for some of the most common tumors can benefit from the research that is being done on the veterinary side,” Rönnberg said. “The precision treatments we are seeing researchers work on leverage biological similarities and allow treatments to be tailored for the best outcome and least side effects in any cancer patient, whether human or other animal.”
AdvaVet is currently working on a number of projects that may benefit both pets and their owners. XR17 is a patented nanomedical delivery technique that improves the safety and efficiency of chemotherapy administered to both animals and humans. AdvaVet is currently testing XR17 with paclitaxel, a widely used treatment for various cancers in humans, which has severe side effects that the company hopes to curb. It is also testing a form of doxorubicin, another common chemotherapy for people, which can cause heart damage.
“The hope is that our doxorubicin formulation can help decrease the effects on the heart,” Rönnberg explained. “Even if we do not see significant differences in cardiotoxicity... our studies will help plan the treatment more effectively by allowing us to see signs of cardiotoxicity earlier.
“Catching these side effects early gives us a better chance to design the monitoring of the patients around the possibility of cardiotoxicity as a side effect, which will likely increase quality of life as well as reduce the harmful effects on the heart.”
Both Rönnberg and Abadie explain that veterinary oncology is not animal testing, but a genuine expression of the relationship between people and their pets. Animals brought into clinical trials are enrolled by their owners, who may be compensated for their time. (Pet owners in Abadie’s studies were not financially compensated.) Visits are made out of concern for the pet and benefit owners who might not be able to otherwise afford prohibitively expensive treatment.
Researchers are required to comply with local regulations regarding animal welfare and testing. In addition to obtaining the approval of clinical trial ethics committees, they must have the continued consent of owners, who typically take their pets home between appointments and can opt out of trials at any time. In cases of uncontrollable symptoms, researchers will also, at the request of their owners, euthanize animals.
After all, these “patients” are pets.
“These could be any dogs unfortunately affected by cancer,” Abadie said. “It could be yours or mine.”
