By Lauren Westerhold
Chances are you know someone who has been diagnosed with cancer. And even if you don’t, one of your friends knows someone with cancer. As many as 1.6 million new cases of cancer of any type have been diagnosed in the U.S. since the start of 2013, and about 500,000 have died from cancer this year, according to the American Cancer Society. Among the most common of standard treatment options, along with surgery and radiation therapy, is chemotherapy, and the laundry list of side effects associated with this treatment are well-known. Fatigue, hair loss, and nausea are among the most generally recognized side effects, but there is another that is extremely debilitating and not nearly as widely recognized: “peripheral neuropathy.”
Peripheral neuropathy causes severe tingling, numbness, and pain in the arms, hands, legs, and feet of cancer patients undergoing chemotherapy, and this does not always go away after stopping chemotherapy. Patients who have undergone chemotherapy may suffer pain in their limbs for the rest of their lives, and that is because this sort of nerve damage is usually permanent. I remember my uncle recounting stories of his palms being so sore that he couldn’t turn a doorknob when he was receiving chemotherapy. This is just one example of how it complicates the lives of cancer patients whose battles are already painful enough. Unfortunately, peripheral neuropathy doesn’t receive nearly as much attention as other life-altering conditions, simply because it isn’t fatal.
“Okay, so what do we do about it?”
Fortunately, a team of researchers at the Neuromuscular Division of Johns Hopkins University School of Medicine may be closer to answering that question, and the answer might involve – wait for it – a dog food additive.
“Dog food additive? That’s gross! How on earth could that help?”
Excellent question. Apparently, when a patient’s body is stressed, as it certainly is during chemotherapy, his or her cells make exponentially more of a certain protein (which goes by the name of Hsp90), and it is believed that this protein is what begins the process of nerve degeneration. The dog food additive, an antioxidant by the name of ethoxyquin, binds to Hsp90 and prevents it from interacting with two other key proteins that build up in patients with neuropathy, though the exact mechanism is still currently unknown. Fun fact: one of these other proteins, called ataxin-2, has also been implicated in nerve damage associated with Lou Gehrig’s disease.
This additive has only been used in mice thus far, but its results are very promising. When mice were given chemotherapy without the additive, they experienced nerve degeneration in their paws within two weeks. Mice that were given both chemotherapy and the additive, however, experienced almost 70 percent less nerve damage.
Ahmet Höke, M.D., is the first author of this study, and he and his team of researchers are hoping to develop a way to use this additive as a pre-treatment for cancer patients anticipating chemotherapy in order to prevent possible nerve damage, in much the same way as anti-nausea medications are given currently.
“That’s really cool, but are there any bad side effects of giving people this additive?”
While the safety of the chemical has not been studied in humans, it is known that heavy exposure to ethoxyquin can cause harm to dogs. However, Höke says that the concentration needed for the chemical to do its job in humans would be about 20 to 30 times lower than the concentration found in commercial dog food, so it seems that this is low enough not to have any side effects of its own.
Who knew a potential solution to one of chemotherapy’s most debilitating side effects has been sitting in our pets’ food bowls all this time? Hopefully, in time, we will see this treatment being used to improve the lives of cancer patients and empower them on their fight towards remission.
Höke, A., et al. (2013). Ethoxyquin prevents chemotherapy-induced neurotoxicity via Hsp90 modulation. Annals of Neurology, Accepted Article. DOI: 10.1002/ana.24004
Cancer Facts & Figures 2013. American Cancer Society. Retrieved from http://www.cancer.org/research/cancerfactsstatistics/cancerfactsfigures2013/index
Coping with Cancer: Supportive and Palliative Care. National Cancer Institute at the National Institutes of Health. Updated 12/10/2012. Retrieved from http://www.cancer.gov/cancertopics/coping/physicaleffects/chemo-side-effects
Peripheral Neuropathy. Mayo Clinic. Updated 08/13/2013. Retrieved from http://www.mayoclinic.com/health/peripheral-neuropathy/DS00131