Odds are, any dog lover will tell you her four-legged companion is truly her best friend. And no wonder; it turns out we have more in common with Fido than our shared love for peanut butter and long walks on the beach. Dogs and humans share a nearly identical tumor marker that may one day lead to new therapeutic treatments for both species.

University of Veterinary Medicine researchers in Vienna, Austria were looking for similarities between breast cancer in dogs and humans when they discovered a single molecule responsible for the migration of cancer cells that has evolved so little it is practically unchanged between the two species.

Cancer markers are molecules occurring in blood or tissue that are associated with cancer and whose measurement or identification is useful in patient diagnosis or clinical management.

Despite steadily improving methods for diagnosing and treating cancer, the disease still represents one of the most frequent causes of human death. What is less well known is that this also holds true for dogs and other pets, said Erika Jensen-Jarolim, the study’s author.

Dogs get cancer at about the same rate as humans. “And about half the dogs over 10 years old die because they develop a carcinoma that is biologically similar to a human tumor,” she said.

While cancer can occur in any part of a canine’s body, like its human counterparts, breast cancer is the most common tumor in female dogs. One-third to half of all canine mammary tumors are cancerous and 50 to 75 percent of these recur or metastasize in one to two years.

“Because dogs have shorter life-spans than humans, similar processes take place on a shorter time-scale. This means that research in dogs gives faster results. By means of comparative research on the two species – so-called comparative medicine – it might be possible to develop a new generation of diagnostic and therapeutic procedures much, much faster. And these may be applicable both to humans and to animals,” Jensen-Jarolim said.

Subsequent work will address how these binding molecules function in human breast cancer and in cancer of the milk glands in dogs in the search for new therapeutic approaches for both species.

The study, “Tree of Life,” is published in the March 2011 edition of the medical journal, PLoS Currents.

Lynette Summerill is an award-winning writer who lives in Scottsdale, Arizona. In addition to writing about cancer-related issues for EmpowHER, her work has been seen in newspapers and magazines around the world.