Viscum album L. therapy in oncology – an update on current evidence

Aim: A majority of oncological patients apply add-on white-berry European mistletoe (Viscum album L., VA) extracts to reduce disease- and treatment-related symptoms and to improve health-related quality (HRQL) of life. VA extracts exert various antitumor, pro-apoptotic, anti-proliferative and immunomodulatory effects. Two current meta-analyses attribute life-prolonging and HRQL improving properties to additive VA therapy. The aim of the study was to review the current knowledge on VA extracts in clinical oncology. Methods: 290 clinical research articles including systematic reviews and guidelines were screened and analysed for their association with add-on VA therapy in patients with gynaecological, lung or gastrointestinal cancer. Results: We found a good evidence of add-on VA therapy to improve the HRQL of patients with breast cancer (ASCO-endorsed SIO guideline) and of HRQL-improving and survival-prolonging properties of VA therapy in pancreatic cancer. In the field of gastrointestinal, gynaecological and lung cancer, new or updating integrative and/or oncological guidelines should consider clear recommendations on integrative therapies including VA therapy. Nevertheless, further clinical and real-world data trials need to be performed in this field. Conclusion: The present update provides a brief overview regarding the use of VA preparations in clinical oncology reviewing current systematic reviews, randomized controlled and real-world data studies. In addition, current guidelines as to their suggestions in the context of VA therapy are highlighted as evidence in the improved management of cancer and cancer-related side effects for this treatment is accumulating.