Evaluation of Concomitant Use of Anticancer Drugs and Herbal Products: From Interactions to Synergic Activity

Simple Summary Complementary and alternative medicine (CAM) therapies include a wide range of procedures and products that are often used by cancer patients to directly combat cancer and to protect normal cells from the toxic effects of conventional therapies. Most often, their use is self-prescribed based on a collection of scattered information from websites and advice from relatives or friends. In this paper, we examined the potential known benefits and harms associated with the most commonly used alternative treatments to provide a practical guide for caregivers and patients. CAM is used by about 40% of cancer patients in Western Countries, with peaks of 80% for breast cancer patients. Cancer patients use CAM to boost immune function, to control cancer symptoms and treatment-related side effects, and to improve health-related quality of life (HR-QoL) and survival. Unfortunately, self-prescription of natural remedies in cancer patients can lead to unexpected toxicities and can reduce the effectiveness of cancer therapy. Although CAM usually refers to all the "natural or organic" products/methods that are generally considered less toxic, there are concerns about drug interactions, especially in patients participating in clinical trials with experimental agents. Despite the claims of the promising and potential benefits made by prescribers, many CAMs lack clear scientific evidence of their safety and efficacy. Given the widespread use of CAM-both clearly declared and overt-in this review, we focused on the most important known data on the risk of interactions between biologics and oncology drugs with the goal of opening up CAM in accordance with the meaning of integrative medicine.