A Specific Mistletoe Preparation (Iscador-Qu ® ) in Colorectal Cancer (CRC) Patients: More than Just Supportive Care?

Rationale: In 2009 we reported the results of a pharmaco-epidemiological, retrospective observational cohort study in colorectal carcinoma (CRC) patients UICC stage I-III, receiving chemo- and/or radiotherapy together with European Viscum album L. ("Viscum") extract (Iscador ® ) as supportive care (n = 429) versus the conventional treatment (n = 375) after R0 resection (J. Soc. Int. Oncol. 7: 173-145). The endpoints have been therapy induced adverse effects, disease symptoms and disease-free survival (DSF). Objective: Here, we present the secondary and confirmatory analysis of this original data set with respect to the host tree specificity of Viscum. Results: Patients receiving the extract from Viscum harvested from oak (Quercus) trees, Iscador ® Qu (Isc- Qu), in a supportive care mode simultaneously with chemo- and/or radiotherapy (n = 106) showed a significant improvement in therapy induced adverse effects, and, most remarkable, a significant delay of metastasis formation and longer DFS compared to conventionally treated patients (n = 212) (control). To make the analysis more robust, patients treated by the chemo- and/or radiotherapy protocols were also analyzed and stratified for the UICC I-III stages. Accordingly to the overall Kaplan-Meier analysis result, patients receiving Isc-Qu as supportive care presented significantly longer median time to distant metastases formation (metastasis-free survival, MFS) within the course of the observational cohort study (133+ months (Isc-Qu) versus 94 months (control), p (Log Rank) = 0.002. In the Cox regression analysis, the confounder-adjusted hazard ratio, HR, (95% confidence interval) came up to HR (metastasis) = 0.31 (0.13-0.711), p = 0.006. This result indicates an estimated 69% metastasis-hazard- reduction in the Isc-Qu group relative to the controls. In summary, patients concomitantly treated by Iscador ® showed fewer persisting disease- and therapy-induced symptoms and the DSF hazard ratio suggested a survival benefit. Clinical implication: This secondary and confirmatory analysis of the original data set suggests that a mistletoe (Viscum) preparation, harvested from oak (Quercus) trees (Isc-Qu), appears to be a naturally tailored molecular composition to target CRC patients by reducing therapy-related adverse effects, improving the cancer- related symptoms and showing a potential to increasing the metastases-free survival. Limitations: The effect on prolonged survival should be interpreted with some caution because the applied study design shares some potential risk for bias common to all non-randomized observational studies. Also, potential biases were tried to minimize by systematic multivariable adjusting of end point criteria for baseline imbalance, treatment regimen, and other potential confounders.