Mistletoe effect bij kanker blijft onzeker
De resultaten van de meta-analyse waren aldus:
Eighty studies were identified. Fifty-eight were excluded for various reasons, usually as there was no prospective trial design with randomised treatment allocation.
Of the 21 included studies 13 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 of mistletoe treatment; overall comprising 3484 randomised cancer patients.
Interventions evaluated were 5 preparations of mistletoe extracts from 5 manufacturers and one commercially not available preparation. The general reporting of RCTs was poor.
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.
De conclusie in alledaagse bewoordingen was:
Preparations from the European mistletoe (Viscum album L.) are among the most prescribed drugs in cancer patients in several European countries. Proponents claim that mistletoe extracts stimulate the immune system, improve survival, enhance quality of life and reduce adverse effects of chemo- and radiotherapy in cancer patients.
The review found that there was not enough evidence to reach clear conclusions about the effects on any of these outcomes and it is therefore not clear to what extent the application of mistletoe extracts translates into improved symptom control, enhanced tumour response or prolonged survival.
Adverse effects of mistletoe extracts were reported, but appeared to be dose-dependent and primarily confined to reactions at injection site and mild, transient flu-like symptoms. In the absence of good quality, independent trials, decisions about whether mistletoe extracts are likely to be beneficial for a particular problem should rely on expert judgement and practical considerations.
Horneber MA, Bueschel G, Huber R, Linde K, Rostock M. Mistletoe therapy in oncology. Cochrane Database of Systematic Reviews 2008, Issue 2. Art. No.: CD003297. DOI: 10.1002/14651858.CD003297.pub2.