Cancer is so prevalent, and not just in humans. About one in three people will develop cancer during their lifetimes, according to the American Cancer Society. Similarly, about one in four dogs will develop cancer at some stage in their life, reports the Veterinary Cancer Society. Almost half of dogs over the age of 10 will get it, and it's the leading cause of death in dogs that age.

One reason so many dogs end up with cancer is because of advances in veterinary medicine. Dogs are living longer and, with longevity comes the development of more disease.

Although that's good and bad news for dogs and the owners who love them, it's definitely good for human cancer research.

There's a developing field called comparative oncology that studies the similarities between human and animal cancers, hoping that the research will lead to ways to treat cancer more effectively.

"The genetic difference between humans and dogs is quite small," Dr. Rodney Page, professor of medical oncology and director of the Flint Animal Cancer Center at Colorado State University, told NBC News. "Humans and dogs are 95 percent identical genetically — and the diseases that affect humans including breast cancer, prostate cancer, and melanoma are almost identical."

Comparing canine and human cancer

The similarities between human and canine cancer are so important that the National Cancer Institute has a Comparative Oncology Program with clinical trials and funding set aside to study how cancer in dogs can be used to study cancer in humans.

"We want to understand and be able to provide treatment for dogs for their sake and for the families that love them. But also, they serve as a bridging species," Dr. Amy LeBlanc, DVM, staff scientist and director of the program, tells MNN. "The cancers they get develop naturally in the course of their life, and aren't contrived ... Studying cancer in dogs can help us develop new diagnostic strategies for humans."

Comparing canine cancer to human cancer can be more accurate than using laboratory animals. Experiments in mice don't necessarily translate to humans, plus the tumors that occur in the lab aren't naturally occurring.

The program also coordinates and manages clinical trials through a network of veterinary schools in the U.S. and Canada. Dogs could potentially be eligible for new opportunities in cancer medications and diagnostics that could benefit the pet and aid human research at the same time.

"We have an opportunity help advance drugs that are promising for the human side by studying them in dogs first. We can weed out poor candidates in dogs first, which means better outcomes for people," LeBlanc says.

"It's probably premature to say that dogs are going to be the answer to curing cancer. But there is value to be had in studying them and coming up with new diagnostic strategies and treatments."

Taking part in clinical trials

dog receiving treatment Dogs can take part in clinical trials that might treat their disease and also advance human cancer studies. (Photo: Dmitry Kalinovsky/Shutterstock)

Pet owners who want to look into clinical trials can visit the animal health studies database run by the American Veterinary Medical Association. You can search by diagnosis, field of veterinary medicine and species, and then narrow the findings by location to see if there's a clinical trial for which your pet is qualified.

In addition to receiving access to cutting-edge treatments, there may also be financial incentives for taking part. Clinical trials run by the Comparative Oncology Program are at least partially funded, but most often fully funded, with only some upfront costs to make sure the dog is eligible for the trial.

"Dog owners have a menu of choices. The owner can say I’m interested in a clinical trial, more conventional therapy, like chemotherapy or surgery, or palliative, end-of-life care," says LeBlanc. "A clinical trial may or may not be a direct benefit to their dog but they get top-notch medical care and the added benefit that they're adding to a body of knowledge that will not only help the pet-owning public, but they’re contributing significantly to the body of knowledge that helps us develop better treatments and diagnostic strategies for humans."

It's a symbiotic relationship that could bring about significant changes in treatment. In fact, this documentary — a team effort between researchers at Colorado State University and comparative oncology leaders around the country — sums it up beautifully, and its name says it all: "The Answer to Cancer Might Be Walking Beside Us."

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.

How dogs are helping us understand cancer
Comparative oncology uses what we learn about animal cancers to help treat humans.