A meta-analysis of trials on the use of mistletoe extract to treat cancer failed to show efficacy, report UK researchers in the International Journal of Cancer.
Mistletoe, part of a Christmas tradition, is also widely used in the treatment of cancer but the results of clinical trials are highly inconsistent, writes Edzard Ernst from the Peninsula Medical School in the UK and colleagues in Germany.
The team conducted a systematic review of all randomised clinical trials of mistletoe therapy, using eight databases to identify studies that met the inclusion criteria. Data were independently validated and extracted by two authors and checked by the third according to predefined criteria.
Statistical pooling was not possible because of the heterogeneity of the primary studies. Therefore a narrative systematic review was conducted, including 10 trials.
"Most of the studies had considerable weaknesses in terms of study design, reporting or both," write the team.
Some of the weaker studies implied benefits of mistletoe extracts, particularly in terms of quality of life, but none of the methodologically stronger trials exhibited efficacy in terms of quality of life, survival or other outcome measures, they concluded.