Oncologists Need to Ask About Herbs and Supplements

Roxanne Nelson, RN

February 23, 2015

A large percentage of cancer patients use complementary and alternative medicine (CAM), including herbs and supplements, while undergoing treatment. However, fewer than half of US oncologists ever initiate discussions about the use of these products, according to the results of a new survey.

In addition, two thirds of those surveyed reported that a lack of knowledge about this subject was a major barrier to having conversations with their patients, despite the fact that some herbal products can interact with cancer treatments.

"The popularity of complementary and alternative medicine in cancer treatment continues to grow, and research has shown that oncologists are generally supportive of such modalities in treating curable cancers," said lead author of the study Richard Lee, MD, medical director of the Integrative Medicine Program at the University of Texas MD Anderson Cancer Center, in Houston, in a statement.

"However, discussions among physicians and patients about herbs and supplements are not the norm, and doctors may underestimate use among patients," he added. "We hope this encourages physicians to learn more about commonly used herbs and supplements and to more frequently ask their patients about them."

On average, Dr Lee and his team found that oncologists discussed use of herbs and supplements with only 41% of their patients, and only a quarter (26%) of these discussions were initiated by the oncologist.

More than half (59%) reported that they had not received any education about this topic.

But despite this, the vast majority of oncologists (93%) reported being concerned about potential interactions between these products and ongoing treatments, as well as about how much money patients spend on them (89%).

The study is published in the Journal of Clinical Oncology.

Only a few studies have explored the prevalence of toxic interactions between herbs and supplements and cancer therapy, note the authors. In one study, for 136 herb-drug combinations, 47 potential interactions were identified, although data on potential interactions for almost half of the herbs are not available (Integr Cancer Ther. 8:29-36,2009).

Some research on antioxidant vitamins has shown that when head/neck cancer patients used them during radiation therapy, there was a trend toward increased cancer recurrence and second primary cancers, noted Dr Lee. "Thus, while the clinical impact of use during cancer therapy remains unclear, the potential for harm does exist."

Discourage Use in Curable Disease

Dr Lee and colleagues conducted the survey in order to explore oncologists' knowledge, attitudes, and practice patterns regarding the use of herbs and supplements by their patients. A survey was sent randomly to 1000 members of the American Society for Clinical Oncology; 392 responded and were included in the analysis.

Most of the respondents were male (71%) and white (75%), with a mean age of 48 years. More than half (58%) reported practicing in the community, and one third of the oncologists said that they had personally used CAM therapies in the previous year.

Only 26% of oncologists initiated a discussion about the use of herbal products and supplements. Physician factors associated with having initiated these discussions included female sex, higher self-reported knowledge, prior education about these products, increased knowledge about their potential adverse effects and interactions, and estimating a higher prevalence of use among patients.

Most of the respondents (86%) reported treating at least one patient in the previous 12 months with chemotherapy who was concurrently using herbs/supplements. On average, they estimated that they had provided chemotherapy to 19 such patients during the past year.

When presented with a hypothetical patient who had a potentially curable cancer, 80% of oncologists said that they would discourage the use of herbs/supplements with chemotherapy. But when they were presented with a hypothetical patient with an incurable cancer, only 37% would do so (48% remained neutral).

But curable or not, 90% reported that they would likely provide chemotherapy, even if the patient insisted on using the unknown herb.

"Given the high prevalence of herb/supplement use by patients and the potential for adverse interactions with some cancer treatments, future efforts should seek to improve oncologists' knowledge about herbs/supplements," conclude the authors. "Such efforts may lead to more open discussions with patients about this important topic, thereby improving patient care."

The study was supported by an American Society of Clinical Oncology Cancer Foundation Young Investigator Award (to Dr Lee) and by the National Cancer Institute. The other authors have disclosed no relevant financial relationships.

J Clin Oncol. 2014;32:4095-101. Abstract

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