Alternative therapies in veterinary cancer: What are the risks?

August 25, 2019
Rebecca A. Packer, MS, DVM, DACVIM (Neurology/Neurosurgery)

Dr. Packer is an associate professor of neurology/neurosurgery at Colorado State University College of Veterinary Medicine and Biomedical Sciences in Fort Collins. She is active in clinical and didactic training of veterinary students and residents and has developed a comparative neuro-oncology research program at Colorado State University.

A veterinary oncologist outlines what every veterinarian should know when counseling owners on complementary and alternative medicine treatments for their cancer patients.

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According to a survey by the Flint Animal Cancer Center at Colorado State University, about three-quarters of pet owners have used complementary or alternative medicine (CAM) for their pets with cancer.1 Yet, how many of us clinicians are well versed in these therapies?

As Michael O. Childress, DVM, MS, DACVIM (Oncology), pointed out during his lecture at Fetch dvm360 conference in Kansas City, our lack of knowledge is due in part to the paucity of evidence-based literature on the subject. Given the popularity of CAM therapies, he said, it's important to be aware of these treatments in order to counsel owners appropriately as to their use, efficacy, value and the potential risks to their pet. Dr. Childress shed light on some of the commonly used CAM therapies and offered a number of resources clinicians can consult for more information.

Broadly, CAM therapies include medicinal, nutritional, physical, mental or spiritual treatments. Few, if any, of these therapies have shown clinical anticancer effects. It's important to be aware of this limitation and counsel owners that their expectations regarding direct anticancer benefits may be unrealistic. CAM therapies should not be used in lieu of established anticancer therapies; rather, they should be used as adjunctive therapies or to ameliorate the side effects of therapy (e.g. nausea or pain).2

Ready for a deeper dive?

Dr. Childress recommended several print and online resources for veterinary professionals who want to learn more about CAM therapies:

> Fetrow CH, et al. Professional's Handbook of Complementary and Alternative Medicines. 3rd ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2003.

> American Cancer Society. American Cancer Society Complete Guide to Complementary and Alternative Cancer Therapies. 2nd ed. Atlanta, GA: American Cancer Society; 2009.

> Robinson NG. Complementary and alternative medicine for patients with cancer. In: Withrow SJ, Vail DM, Page RL, eds. Small Animal Clinical Oncology. 5th ed. St. Louis, MO: Saunders-Elsevier; 2013:280-292.

> National Center for Complementary and Integrative Health website: nccih.nih.gov

> American Cancer Society website: cancer.org

> National Cancer Institute website: cancer.gov/cancertopics/cam

Potential risks of CAM therapies

Dr. Childress discussed four ways in which CAM therapies may be harmful to veterinary patients:

CAM therapies may cause direct toxicity or injury to the patient. For example, escharotics (herbal preparations that contain parts of the bloodroot plant) have the potential to cause significant tissue injury.3

Interactions between established and CAM therapies may result in toxicity or injury. For example, over-the-counter botanical medications are poorly regulated and thus may contain potentially harmful biologically active components that may interact with cytochrome P450 or P-glycoprotein to alter the metabolism and efficacy of other drugs, including standard chemotherapeutics.4,5

Interactions between established and CAM therapies may decrease the efficacy of the established therapies. For example, although antioxidants themselves (including vitamin E) are not harmful, they may reduce the efficacy of therapies that produce free radicals as their anticancer mechanism of action (e.g. radiation therapy, some chemotherapeutics).

Pet owners who opt for CAM therapies may delay or avoid starting their pet on established anticancer therapies. Consider cannabinoids. Both cannabidiol (CBD) and tetrahydrocannabinol (THC), the two most investigated cannabinoids,6,7 also are poorly regulated with little oversight of the manufacturing process. These compounds may cause adverse effects or toxicity in the patient, have potentially unwanted effects (including antioxidant effects, among others) and have limited evidence for appropriate tissue or blood concentrations to achieve an anticancer effect, if an anticancer effect is even achievable in a clinical setting (evidence to date is limited to cancer models).

Acupuncture and cancer

Alternatively, one of the CAM therapies that may have a viable adjunctive role in treating cancer patients is acupuncture. There is some evidence to show that acupuncture mitigates chemotherapy-associated nausea and helps manage pain (although these studies evaluating acupuncture for pain management were not performed on pets with cancer- or cancer therapy–related pain).8,9

Maintain open, compassionate client communication

Also of note from the Flint Animal Cancer Center survey mentioned earlier: Of the pet owners who reported having tried CAM therapies on their sick animals, a whopping 85% had not talked about CAM therapies with their veterinarian.1 Dr. Childress emphasized throughout his lecture that one of the more important aspects of treating cancer in pets is to maintain open and compassionate dialogue with their owners. Talk to your clients about CAM therapies so that they feel comfortable being honest about their use and are more accepting of the information presented about the potential benefit or harm of these therapies.

References

1. Lana SE, Kogan LR, Crump KA, et al. The use of complementary and alternative therapies in dogs and cats with cancer. J Am Anim Hosp Assoc 2006;42(5):361-365.

2. Raditic DM, Bartges JW. Evidence-based integrative medicine in clinical veterinary oncology. Vet Clin North Am Small Anim Pract 2014;44(5):831-853.

3. Jellinek N, Maloney ME. Escharotic and other botanical agents for the treatment of skin cancer: A review. J Am Acad Dermatol 2005;53(3):487-495.

4. Shord SS, Shah K, Lukose A. Drug-botanical interactions: A review of the laboratory, animal, and human data for 8 common botanicals. Integr Cancer Ther 2009;8(3):208-227.

5. Sparreboom A, Cox MC, Acharya MR, et al. Herbal remedies in the United States: potential adverse interactions with anticancer agents. J Clin Oncol 2004;22(12):2489-2503.

6. Brutlag A, Hommerding H. Toxicology of marijuana, synthetic cannabinoids, and cannabidiol in dogs and cats. Vet Clin North Am Small Anim Pract 2018;48(6):1087-1102.

7. Pellati F, Borgonetti V, Brighenti V, et al. Cannabis sativa L. and nonpsychoactive cannabinoids: Their chemistry and role against oxidative stress, inflammation, and cancer. Biomed Res Int 2018;2018:1691428.

8. Groppetti D, Pecile AM, Sacerdote P, et al. Effectiveness of electroacupuncture analgesia compared with opioid administration in a dog model: A pilot study. Br J Anaesth 2011;107(4):612-618.

9. Silva NEOF, Luna SPL, Joaquim JGF, et al. Effect of acupuncture on pain and quality of life in canine neurological and musculoskeletal diseases. Can Vet J 2017;58(9):941-951.

Dr. Packer is an associate professor of neurology/neurosurgery at Colorado State University College of Veterinary Medicine and Biomedical Sciences in Fort Collins. She is active in clinical and didactic training of veterinary students and residents and has developed a comparative neuro-oncology research program at Colorado State University.