Prospective controlled cohort studies on long-term therapy of breast cancer patients with a mistletoe preparation (Iscador®)

Background: Mistletoe preparations such as Iscador(R) (Weleda, Schwabisch Gmund, Germany) are commonly used in complementary and alternative/anthroposophic medicine for many cancer indications, particularly for solid cancers. Efficacy of this complementary therapy is still controversial. Objective: Does long-term therapy with Iscador(R) show any effect on survival, tumor progression and psychosomatic self-regulation of patients with breast cancer? Patients and Methods: Prospective recruitment and long-term follow-up of two controlled cohort studies: (1) Randomized matched-pair study (38 pairs): breast cancer patients without any recurrences or metastases and no mistletoe therapy were matched for prognostic factors. By pair-wise random allocation, one of the patients was suggested mistletoe therapy to be applied by the attending physician. (2) Non-randomized matched-pair study (84 pairs): breast cancer patients without recurrences or metastases that already received mistletoe therapy were matched to control patients without Iscador(R) therapy. Results: For overall survival, the non-randomized study shows significant effects in favor of Iscador(R) therapy: hazard ratio HR estimate and 95% confidence interval CI: 0.43 (0.27-0.68). The effect of long-term Iscador therapy on tumor progression as measured by the time to local recurrences, lymphatic or distant metastases in breast cancer patients without any such events at first diagnosis, is in most cases significant in favor of the Iscador group, in the randomized as well as in the non-randomized study. Psychosomatic self-regulation in the Iscador group improves significantly within 12 months compared with the control group in the randomized as well as in the non-randomized study: estimate of the median difference and 95% CI: 0.35 (0.05-0.60), respectively 0.20 (0-0.35). Conclusion: Iscador shows a clinically relevant effect on breast tumor progression as measured by overall survival as well as by the time to recurrences, lymphatic or distant metastases. In the short term, psychosomatic self-regulation increases more markedly under complementary Iscador therapy than under conventional therapy alone.