Review Article: Influence of Viscum album L (European Mistletoe) Extracts on Quality of Life in Cancer Patients: A Systematic Review of Controlled Clinical Studies

Objective. To evaluate controlled clinical studies on the efficacy and effectiveness of Viscum album for quality of life (QoL) in cancer. Materials and methods. The authors conducted a search of 7 electronic databases and reference lists and had extensive consultations with experts. They carried out a criteria-based assessment of methodological study quality. Results. The authors identified 26 randomized controlled trials (RCTs) and 10 non-RCTs that investigated the influence of V album extracts (VAEs) on QoL in malignant diseases; 26 studies assessed patient-reported QoL. Questionnaires were mostly well established and validated. Half of the studies investigated VAEs concomitant with chemotherapy, radiotherapy, or surgery. Some studies were well designed, whereas others had minor or major methodological weaknesses. Among the 26 RCTs, 22 reported a QoL benefit, 3 indicated no difference, and 1 did not report any result. All the non-RCTs reported a QoL benefit. Of the studies with higher methodological quality, most reported a benefit, whereas 1 found no difference. Improvements were mainly in regard to coping, fatigue, sleep, exhaustion, energy, nausea, vomiting, appetite, depression, anxiety, ability to work, and emotional and functional well-being in general and, less consistently, in regard to pain, diarrhea, general performance, and side effects of conventional treatments. VAEs were well tolerated. Conclusions. VAEs seem to have an impact on QoL and reduction of side effects of conventional therapies (chemotherapy, radiation) in experimental trials as well as in routine daily application. The influence on fatigue especially should be investigated further.