High-Dose Viscum album Extract Treatment in the Prevention of Recurrent Bladder Cancer: A Retrospective Case Series.

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.