Use and Safety of Viscum album L Applications in Cancer Patients With Preexisting Autoimmune Diseases: Findings From the Network Oncology Study.

BackgroundViscum album L (VA, mistletoe) extracts are commonly used in integrative oncology. Here the clinical safety profile of additional VA-treatments to standard care in cancer patients with preexisting autoimmune diseases was analyzed.MethodsIn this observational cohort study medical data and recorded adverse events (AEs) of treated patients were retrieved from the Network Oncology registry and a safety analysis was performed.ResultsA total of 106 patients (median age 63 years) treated with add-on VA-extracts were analyzed. Most frequent autoimmune diseases were Hashimoto's thyroiditis (27%), psoriasis (19%), and ulcerative colitis (15%). Seventeen patients (16%) experienced VA-related AEs, but neither long-term side effects nor VA-therapy discontinuations were recorded. In a subgroup of 30 patients receiving long-term VA-therapy no exacerbations or flares of underlying autoimmune diseases were recorded. Additionally, a significant halving of overall AE-rates was observed during VA-treatment periods (p= 0.019).ConclusionsOur findings suggest that add-on VA-therapy in cancer patients with preexisting autoimmune diseases as Hashimoto's thyroiditis, psoriasis, ulcerative colitis, Grave's disease, and some rheumatic diseases is safe. No higher rates of VA-associated AEs were observed and the overall AE-rates were significantly lowered in VA-therapy periods. However, results should be interpreted with caution in light of the study's observational character.