By Dr. Becker
An assistant professor at the University of Pennsylvania School of Veterinary Medicine, Dr. Nicola Mason, is researching a new way to treat canine osteosarcoma.
Osteosarcoma is an all too common and highly aggressive bone cancer that invades the long bones of large and giant breed dogs. Even with amputation of the affected limb and chemotherapy – the current standard of treatment – the average survival rate is only about a year. Small clusters of cancer cells develop into metastatic tumors that are ultimately fatal. Approximately 60 percent of dogs with osteosarcoma die within one year of diagnosis.
Dr. Mason of Penn Vet, in collaboration with Advaxis Corporation, is currently studying a vaccine that kills osteosarcoma cancer cells that survive chemotherapy treatments. The vaccine contains a genetically modified bacteria, Listeria, that expresses a tumor marker called Her2/neu. The Her2/neu protein is also commonly associated with breast cancer cells in women. This target is expressed in about 40 percent of canine osteosarcomas. The theory behind the vaccine is that it will stimulate the immune system to kill the bacteria and also the cells that express Her2/neu.
According to Dr. Mason, if the vaccine is able to effectively stimulate the immune system, then immune cells will find and destroy any remaining cancer cells that have survived chemotherapy. It is also intended that the immune system will be left with a memory of the cancer cells and will be able to inhibit development of further osteosarcoma lesions.
The vaccine is given intravenously to dogs that have been diagnosed with osteosarcoma that expresses the Her2/neu target. To date, Dr. Mason has administered the vaccine to a dozen dogs with osteosarcoma after amputation and chemotherapy. The vaccine is given once weekly for three weeks, and the only reported side effect thus far is a mild, transient fever.
Preliminary Results and Future Plans for the Vaccine
Preliminary results of the vaccine's effectiveness have been very encouraging. As of mid-November 2013, the very first dog vaccinated was still alive at 570 days post-diagnosis. Two additional dogs were alive and cancer free for over 500 days post-diagnosis, and other more recently vaccinated dogs were also doing well.
In the future, Dr. Mason hopes to include another group of dogs in her vaccine study – these are dogs diagnosed with osteosarcoma that can't undergo amputation of the affected limb due to neurological or musculoskeletal issues in other limbs. Treatment of these dogs involves alleviating the pain caused by the tumor.
Dr. Mason is also looking into the possibility that the vaccine may help prevent osteosarcoma in certain breeds at high risk for developing the disease.
My View on a Bacteria-Based Vaccine to Treat Osteosarcoma
As regular readers of the Healthy Pets newsletter know, my general opinion of vaccines is that they should be used with extreme caution and only when truly necessary to protect a vulnerable animal from a specific disease. In fact, many of our readers have an automatic negative response to even the mention of the word "vaccine." Most of the adverse reactions and side effects associated with vaccines come from the toxic adjuvants they contain.
In this case, even though the product is called a vaccine, it's really more of an unadjuvanted form of immunotherapy. A newly developed product is being studied for its ability to treat an aggressive, life-ending cancer, and I'm not opposed to non-toxic immunotherapy. This is assuming the side effects truly are mild and short-lived, and improvement is achieved in both the quantity AND quality of the dogs' lives.
Needless to say, I feel much less comfortable with the prospect of vaccinating healthy dogs that may be at increased risk for osteosarcoma, since vaccines can cause significant damage to immune system functioning and are linked to certain types of cancers.
My recommendation is to create a lifestyle for your pet that will reduce his risk of developing cancer.
5 Ways to Reduce Your Dog's Cancer Risk
Don't allow your dog to become overweight. Studies prove that restricting the amount of calories an animal eats prevents and/or delays the progression of tumor development across species, including canines.
Fewer calories cause the cells of the body to block tumor growth, whereas too many calories can lead to obesity, and obesity is closely linked to increased cancer risk in humans. There is a connection between too much glucose, increased insulin sensitivity, inflammation, and oxidative stress – all factors in obesity – and cancer.
It's important to remember that fat doesn't just sit on your pet's body harmlessly. It produces inflammation that can promote tumor development.
Feed an anti-inflammatory diet. Anything that creates or promotes inflammation in the body increases the risk for cancer. Current research suggests cancer is actually a chronic inflammatory disease. The inflammatory process creates an environment in which abnormal cells proliferate.
Cancer cells require the glucose in carbohydrates to grow and multiply, so you want to limit or eliminate that cancer energy source. Carbs to remove from your pet's diet include processed grains, fruits with fructose, and starchy vegetables like potatoes. Keep in mind that all dry pet food contains some form of starch. It may be grain-free, but it can't be starch-free because it's not possible to manufacture kibble without using some type of starch.
Cancer cells generally can't use dietary fats for energy, so appropriate amounts of good quality fats are nutritionally healthy for dogs.
Another major contributor to inflammatory conditions is a diet too high in omega-6 fatty acids and too low in omega-3s. Omega-6s increase inflammation while the omega-3s do the reverse. Processed pet food is typically loaded with omega-6 fatty acids and deficient in omega-3s.
A healthy diet for your pet – one that is anti-inflammatory and anti-cancer – consists of real, whole foods, preferably raw. It should be high in high-quality protein, including muscle meat, organs and bone. It should include moderate amounts of animal fat and high levels of EPA and DHA (omega-3 fatty acids), a few fresh cut veggies and a bit of fruit.
This species-appropriate diet is high in moisture content and contains no grains or starches. I also recommend adding a vitamin/mineral supplement and a few beneficial supplements like probiotics, digestive enzymes, and super green foods.
Reduce or eliminate your dog's exposure to toxins. These include chemical pesticides like flea and tick preventives, lawn chemicals (weed killers, herbicides, etc.), tobacco smoke, flame retardants, and household cleaners (detergents, soaps, cleansers, dryer sheets, room deodorizers).
Because we live in a toxic world and avoiding all chemical exposure is nearly impossible, offer a periodic detoxification protocol to your pets.
Allow your dog to remain intact (not neutered or spayed), at least until the age of 18 months to two years. Studies have linked spaying and neutering to increasing cancer rates in dogs. A 2002 study established an increased risk of osteosarcoma in both male and female Rottweilers neutered or spayed before the age of one year.1 Another study showed the risk of bone cancer in neutered or spayed large purebred dogs was twice that of intact dogs.2
Refuse unnecessary vaccinations. Vaccine protocols should be tailored to minimize risk and maximize protection, taking into account the breed, background, nutritional status and overall vitality of the dog. The protocol I follow with healthy puppies is to provide a single parvo and distemper vaccine at or before 12 weeks, and a second set after 14 weeks. I then titer (ask your vet to run titers at a lab that uses the IFA method) two weeks after the last set and if the dog has been successfully immunized, he is protected for life.
If titer tests indicate vaccine levels are low (which would be incredibly unlikely), I recommend a booster for only the specific virus or viruses that titered low, and only for those to which the animal has a real risk of exposure. I do not use or recommend combination vaccines (six to eight viruses in one injection), which is the standard yearly booster at many veterinary practices.