Complementary & Alternative Therapy Use in Clinical Trials

A recent review presented by Christy S. Harris, PharmD, BCOP, Associate Professor, Pharmacy Practice, MCPHS-Boston, at the 2019 HOPA Annual Conference, presented available data and resources to evaluate potential adverse interactions that complementary and alternative medicines (CAMs) may pose to the health of cancer patients and to assess these therapies’ impact on a clinical trial drug.

Generally, CAM has had a negative impact on survival rates among cancer patients, increasing mortality risk in breast cancer (by six-fold), lung cancer (by two-fold), and colorectal cancer (by four and a half fold) patients. Also, patients who are most likely to use alternative medicine to treat their cancers tend to be patients with:

• Breast or lung cancer
• Higher income
• Reside in the Intermountain West or Pacific United States
• Have stage II or III Cancer
• Possess low comorbidity scores

A recent survey of 4,038 adults, 1,001 of whom had a previous or current cancer diagnosis, showed that almost half (47%) of respondents aged 18 to 37 believe that alternative therapies alone can cure cancer. Those numbers do not correspond with the less than 5% of adult cancer patients enrolling in clinical trials, and the researcher notes that “adolescent and young adults have the lowest rate of enrollment on clinical trials.”

Evidence from previous in vitro and animal studies suggest that one such CAM, known as Turmeric (curcumin), can reduce the CYPA1A enzyme, primarily in the liver. However, this drug may also induce the same enzyme in the intestines. Turmeric can also have adverse interactions with such medications as anticoagulants (increasing the risk of bleeding), and Aspirin (elevating cytotoxic levels).

Another alternative medication used for cancer treatment are cannabis and its derivatives, tetrahydrocannabinol (THC) and cannabidiol (CBD). However, cannabis drug interactions are still “largely questionable” due to variability (topical vs. ingested vs. inhaled), and 70% of online CBD products possess either a higher or lower concentration than indicated on their labels.

Ultimately, the Dr. Harris concluded by writing that “making the judgement call” with respect to CAMs should come down to discussions between the clinician, patient, and sponsor, as well as an assessment of the medication’s clinical trial results, the clinical significance of those results, and any adverse effects associated with the alternative medication.