Over 40% of cancer patients use complementary and alternative medications while receiving anticancer treatment.

Background: The use of complementary and alternative medications (CAM) is popular among cancer patients. CAM includes vitamins, minerals, phytotherapy, homeopathy, nutritional supplements and probiotics. CAM use may lead to unwanted risks by interacting with anticancer drugs; therefore, it is important for healthcare providers to be aware of CAM use by their patients. This article describes the prevalence and potential risk of CAM use in an adult Dutch cancer population. This is the first study in which CAM use was investigated using medication reconciliation.

Methods: A descriptive, observational study was conducted at Amsterdam UMC between August 2021 and July 2022. Data regarding the use of CAM was obtained by medication reconciliation reviews with inpatients and outpatients with cancer who received systemic anticancer treatment. Acquired data were evaluated by the research team, and the risks of interactions were classified into relevant, potential, unknown or no interaction. Ultimately, patient-specific recommendations on the use of CAM were provided.

Results: Of the 100 included patients, 73% used CAM during the past year and 41% used CAM actively while receiving anticancer treatment. The most common CAM were vitamins and multivitamins (both 28%). Some 10% of CAM were classified as having a relevant interaction with one or more concurrently used anticancer drugs. No association between age or gender and CAM use was found, while outpatients used significantly more CAM than inpatients (72.7% vs 32.1%; p=0.001). Patients received personalised advice from the hospital pharmacy about their CAM use.

Conclusions: More than 40% of oncology patients investigated in this study used CAM while receiving anticancer treatment, leading to unwanted risks. This prevalence is higher than reported in other studies, possibly due to the use of medication reconciliation interviews. To guarantee safety and efficacy of anticancer treatment, communication between healthcare professionals and patients about CAM is essential.