Chemotherapy Patients Who Take Herbs and Supplements at Risk of Serious Medication Interactions, Study Shows

Patients in study are largely unaware of the risk

Innovations in Cancer | February 2021

Although quite common, cancer patients’ use of herbs and supplements both during and after chemotherapy places them at risk for serious potential medication interactions. That’s the conclusion of a new study from Richard T. Lee, MD, Medical Director of the Supportive and Integrative Oncology Program at UH Seidman Cancer Center. Yet this risk appears to be largely unknown to patients.

“Surprisingly, most patients we interviewed were not worried about potential medication interactions when they were asked about the herbs and supplements that they were taking,” Dr. Lee says. “Yet, more than 88% of the patients taking herbs and supplements were at risk for a major potential medication interactions, and nearly one-third of all herb and supplement interactions were rated as major interactions. The use of herbs and supplements remains prevalent among patients with cancer and may place them at risk for potential medication interactions both during chemotherapy and after the completion of treatment.”

For the study, recently published in the journal Cancer, Dr. Lee and his colleagues conducted telephone surveys with 67 breast cancer and prostate cancer patients who had recently finished chemotherapy at two academic medical centers. Patients were asked questions about all medications they’d taken, including herbs and supplements, before, during and after chemotherapy. The research team then used this information, plus the patients’ medical records, to analyze potential medication interactions using three software programs: Micromedex, Lexicomp, and the Natural Medicines Comprehensive Database.

•  Approximately four-fifths (84%) of patients in the study reported using herbs and supplements, with use increasing after chemotherapy was complete.
• Four out of five patients who used herbs and supplements were deemed by the researchers to be at risk for a major potential medication interaction.
• When comparing patients who used herbs and supplements with those who did not, the researchers found that users were more likely to be at risk for a major potential medication interaction than non-users (92% vs. 70%).
• Nearly half of the potential medication interactions identified as happening during a patient’s course of chemotherapy were rated by the researchers as major.
• The most common type of high-severity potential medication interactions with herbs and supplements involved multivitamins, vitamin D, vitamin E, vitamin C, glucosamine and magnesium.
• When asked if there were concerns about side effects or drug interactions with their use of herbs and supplements, 79% of cancer patients in the study responded ‘no.’

For Dr. Lee, he hopes this small exploratory study will lead both oncologists and primary care providers to more thoroughly discuss with their cancer patients the potential medication interactions associated with herbs and supplements.  The period during and after chemotherapy is especially critical, he says.

“With the highest risk of herb and supplement-related potential medication interactions occurring after chemotherapy, oncologists should ask about herbs and supplement use not only during chemotherapy treatment, but also after treatment completion as patients move into survivorship care,” he says.

He hopes, too, that cancer patients will think twice and get good medical advice before taking herbs and supplements that may interfere with their treatment.

“In our study, the majority of subjects felt confident in receiving advice from their medical team about herbs and supplements and generally would stop taking them if they were told that it would cause an interaction with ongoing chemotherapy,” he says. “Discussions about herbs and supplements by physicians may provide an opportunity to both prevent potential harms and strengthen the physician-patient relationship.”