Side-effects of Phytotherapeutics in Cancer Care - A Review of Inconsistencies in National and International Databases.

Abstract

The interest in phytotherapy in patients with cancer is immensely high. When using herbal medicine, knowledge of potential side-effects is essential as part of counselling the patient. The aim of this study was therefore to collect information on the side-effects of popular medicinal plants and to compare different official and the most popular sources of information reporting the side-effects of phytotherapeutics. Four different databases were reviewed from 09 February 2021 to 01 March 2022. These were the German monographs of the German Federal Institute for Drugs and Medical Devices, the European monographs of the European Medicines Agency, the website About Herbs (https://www.mskcc.org/cancer-care/diagnosis-treatment/symptom-management/integrative-medicine/herbs) and the German Red List. A total of 171 medicinal plants were chosen from the German monographs. These plants were relevant for supportive cancer treatment, targeting symptoms e.g. pain, nausea, vomiting, mucositis or fatigue. Out of the 171 selected plants, only 20 were found in all four sources. The compilation of the data showed there to be a huge disparity in the number of plants listed by each database and the type and frequency of the side-effects described. The reasons for this are manifold: Lack of interest, different interest groups, different origins (Europe versus America) and no standardized terminology. Physicians should not rely exclusively on one source to inform themselves about potential side-effects of phytotherapeutics but should use several sources to ensure the best possible safety of the patient. Since there seems to be too few data on certain medicinal plants for which no side-effects have been documented, more clinical studies are needed.