Interactions in cancer treatment considering cancer therapy, concomitant medications, food, herbal medicine and other supplements.

PURPOSE: The aim of our study was to analyse the frequency and severity of different types of potential interactions in oncological outpatients' therapy. Therefore, medications, food and substances in terms of complementary and alternative medicine (CAM) like dietary supplements, herbs and other processed ingredients were considered. METHODS: We obtained data from questionnaires and from analysing the patient records of 115 cancer outpatients treated at a German university hospital. Drug-drug interactions were identified using a drug interaction checking software. Potential CAM-drug interactions and food-drug interactions were identified based on literature research. RESULTS: 92.2% of all patients were at risk of one or more interaction of any kind and 61.7% of at least one major drug-drug interaction. On average, physicians prescribed 10.4 drugs to each patient and 6.9 interactions were found, 2.5 of which were classified as major. The most prevalent types of drug-drug interactions were a combination of QT prolonging drugs (32.3%) and drugs with a potential for myelotoxicity (13.4%) or hepatotoxicity (10.1%). In 37.2% of all patients using CAM supplements the likelihood of interactions with medications was rated as likely. Food-drug interactions were likely in 28.7% of all patients. CONCLUSION: The high amount of interactions could not be found in literature so far. We recommend running interaction checks when prescribing any new drug and capturing CAM supplements in medication lists too. If not advised explicitly in another way drugs should be taken separately from meals and by using nonmineralized water to minimize the risk for food-drug interactions.

Complementary and alternative medicine (CAM) supplements in cancer outpatients: analyses of usage and of interaction risks with cancer treatment.

PURPOSE: The aim of our study was to analyze the use of complementary and alternative medicine (CAM) supplements, identify possible predictors, and analyze and compile potential interactions of CAM supplements with conventional cancer therapy. METHODS: We included outpatient cancer patients treated at a German university hospital in March or April 2020. Information was obtained from questionnaires and patient records. CAM-drug interactions were identified based on literature research for each active ingredient of the supplements consumed by the patients. RESULTS: 37.4% of a total of 115 patients consumed CAM supplements. Potential interactions with conventional cancer treatment were identified in 51.2% of these patients. All types of CAM supplements were revealed to be a potential source for interactions: vitamins, minerals, food and plant extracts, and other processed CAM substances. Younger age (< 62 years) (p = 0.020, φc = 0.229) and duration of individual cancer history of more than 1 year (p = 0.006, φc = 0.264) were associated with increased likelihood of CAM supplement use. A wide range of different CAM supplement interactions were reviewed: effects of antioxidants, cytochrome (CYP) interactions, and specific agonistic or antagonistic effects with cancer treatment. CONCLUSION: The interaction risks of conventional cancer therapy with over-the-counter CAM supplements seem to be underestimated. Supplements without medical indication, as well as overdoses, should be avoided, especially in cancer patients. To increase patient safety, physicians should address the risks of interactions in physician-patient communication, document the use of CAM supplements in patient records, and check for interactions.