Introduction: Viscum album extract (European mistletoe), containing immuno-active compounds with dose-dependent cytotoxic activity, is being used as an adjuvant cancer treatment in Europe. Few studies have yet been done with high-dose, fever-inducing Viscum album treatment.
Objective: To explore whether subcutaneous injections of high-dose Viscum album have a preventive effect on risk of recurrence of bladder cancer.
Methods: We retrospectively analyzed the case records of patients with resectable bladder cancer who underwent initiation of high-dose Viscum album treatment at our clinic between January 2006 and December 2012.
Main outcome measures: We calculated tumor recurrence and progression risk and explored case records to assess whether treatment had a likely, possible, or unlikely beneficial effect.
Results: Eight patients were identified, 7 of whom had nonmuscle-invasive bladder cancer and 1 with muscle-invasive cancer. Four patients had frequently recurring tumors before treatment. Among the 8 patients, 28 episodes of recurrence were observed. Median tumor-free follow-up duration was 48.5 months. High-dose Viscum album showed a possible beneficial effect in 5 of 8 patients, could not be assessed in 2 patients, and had an uncertain effect in 1 patient. No tumor progression was observed. Treatment was generally well tolerated and no patient stopped treatment because of side effects.
Conclusion: High-dose Viscum album treatment may have interrupted frequently recurring tumors in individual patients with recurrent bladder cancer. Prospective studies are needed to assess whether this treatment offers an additional, bladder-sparing preventive option for patients with intermediate- to high-risk nonmuscle-invasive bladder cancer.. Treatment was generally well tolerated and no patient stopped treatment because of side effects.