Herbal Supplements Are Marketed to Cancer Patients With Little Scientific Support of Safety and Effectiveness

BOSTON—Because so many cancer patients are using dietary supplements, the Integrative Medicine Service of Memorial Sloan-Kettering Cancer Center (MSKCC) created a website (www.mskcc.org/AboutHerbs) that provides scientific information on more than 200 herbs, vitamins, and other dietary supplements commonly used by cancer patients. The website is updated regularly, and receives more than 1.5 million hits a year.

K. Simon Yeung, MBA, PharmD, the clinical coordinator of the site, and his colleagues recently completed a study suggesting that the supplements most commonly used often have the least amount of scientific data validating their safety and effectiveness. He reported the findings at the Society for Integrative Oncology Third International Conference (abstract F065). Dr. Yeung said that use of dietary supplements is high among cancer patients (71%), many of these patients (53%) do not seek the advice of health professionals about their use, and about 23% of dietary supplements are known to have adverse interactions with certain drugs.

Top Five Hits

The researchers identified the five agents on the website receiving the greatest number of hits in the last 6 months. "We assume this reflects the interest in and popularity of the product," Dr. Yeung said. "The top five in descending order were Juice Plus+, lycium, Reishi mushroom, aloe vera, and mangosteen." [See Table for descriptions.]

The researchers then ranked these substances according to the number of related PubMed articles. The results: 1 for Juice Plus+, 145 for lycium, 162 for Reishi, 796 for aloe vera, and 43 for mangosteen. The same general rankings held true for the number of cancer-related clinical trials for each product: 0 for Juice Plus+, 1 for lycium, 6 for Reishi, 10 for aloe vera, and 0 for mangosteen. Therefore, the most popular, Juice Plus+, is supported by the least amount of scientific data, and the fifth most popular, mangosteen, has no clinical data to support its health claims.

In searching the websites of the manufacturers and distributors for information on the marketing and promotion of these supplements, the researchers found that these top five are heavily marketed to cancer patients. "It's disturbing that the health benefits touted by the manufacturers are not supported by scientific data," Dr. Yeung said. "Clearly, marketing has little to do with scientific data."

The heavy promotion of mangosteen, for example, led the investigators to issue a news release on the site warning of "an aggressive effort to promote mangosteen and mangosteen-containing products as dietary supplements using high-pressure sales tactics," and emphasizing that "there is no scientific evidence supporting the use of these products to treat cancer in humans."

Dr. Yeung concluded on a note of caution: "There is no evidence that these products reduce tumor burden or delay progression of disease. Although they appear safe when consumed in moderation, larger amounts may interfere with chemotherapy and may affect blood sugar levels. Cancer patients should be advised that these unproven therapies are not viable substitutes for mainstream cancer treatment."