Retrolective studies on the survival of cancer patients treated with mistletoe extracts: a meta-analysis.

BACKGROUND Studies reveal that patients with cancer are actively seeking supportive treatments and may use distinct coping strategies that might be helpful to extend survival time. In this respect, retrolective studies have been applied to examine the therapeutic potential of adjuvant mistletoe treatment. MATERIAL AND METHODS The databases PubMed, EMBASE, AMED, and CAMbase were used to identify retrolective studies in mistletoe treatment. In addition to a review, we also performed a meta-analysis with respect to cancer patients' survival time by a random effects model. Overall estimates of treatment effects were displayed with a forest plot. RESULTS A total of 17 articles met the inclusion criteria. From these, 10 duplicates and 3 descriptive literature and popular articles had to be removed, leaving 4 retrolective studies on mistletoe preparations and patients' survival conducted between 1985 and 2002, with a total of 3.324 patients (2.454 per protocol) recruited in 17 to 35 German and Swiss hospitals, wards, and private practices. Meta-analysis revealed a moderate overall effect of hazard ratios 0.59 (95% confidence interval 0.50-0.70) in favor of mistletoe treatment. DISCUSSION Although we found a positive treatment effect, there are several methodological limitations with respect to the retrolective study design.