A Cochrane review [Abstract] 1 included 21 studies with a total of 3 484 subjects. 13 studies provided data on survival, 7 on tumour response, 16 on measures of QOL or psychological outcomes, or prevalence of chemotherapy-related adverse effects and 12 on side effects. Interventions evaluated were 5 preparations of mistletoe extracts from 5 manufacturers and one commercially not available preparation.
Of the 13 trials investigating survival, 6 showed some evidence of a benefit, but none of them was of high methodological quality. The results of two trials in patients with melanoma and head and neck cancer gave some evidence that the used mistletoe extracts are not effective for improving survival. Of the 16 trials investigating the efficacy of mistletoe extracts for either improving QOL, psychological measures, performance index, symptom scales or the reduction of adverse effects of chemotherapy, 14 showed some evidence of a benefit, but only 2 of them including breast cancer patients during chemotherapy were of higher methodological quality. Data on side effects indicated that, depending on the dose, mistletoe extracts were usually well tolerated and had few side effects.
Comment: The quality of evidence is downgraded by study quality (several issues) and by imprecise results (limited study size for each comparison).
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