Herb-antitumour drug interaction risks: retrospective integrative oncology study

Objectives The use of herbal medicine is widespread among oncology patients, with potentially negative interactions with anticancer drugs. This study identified herbal products being used among a cohort of oncology patients, assessing the risk for an herb-drug interaction. Methods Herbal medicine use was examined among 42 oncology patients, identifying potential herb-drug interactions using four online sites. The risk for an interaction was scored using the Working Group on Pharmacotherapy and Drug Information of the Royal Dutch Association for the Advancement of Pharmacy (KNMP). Results Most patients (62%) reported herbal medicine use, with 70 products identified; 8 herbs and 13 herbal formulas with unidentified components; and 24 anticancer drugs. Herbal medicine use was more prevalent among female patients (p=0.038), with only nine potential herb-drug interactions identified on at least one site. A maximal KNMP Score of 1 (ie, incomplete published case report) was found with only one interaction. Conclusions The risk for interactions between herbal products and anticancer drugs is difficult to predict, with online search engines providing limited and inconsistent information. Clinical implications of herb-antitumor drug interactions need to be better understood, enabling patients and their oncology healthcare providers to make informed decisions regarding their care.