Twenty-two trials were included in the analysis (containing 46 strata, i.e. sets of patients, tumour stages or localisation). Twelve trials were prospective, five trials were randomised, and five trials had a matched-pair design. The included trials were of moderate to poor quality, in terms of randomisation, matched-pair building, blinding, multicentre and description of drop-outs.
Iscador versus no extra treatment (n=10,641 patients; range 17 to 1,719): Iscador was associated with better survival rates than no extra treatment (overall HR 0.59, 95% CI 0.53 to 0.66), but this was associated with moderate heterogeneity (I2=38.3%, p<0.0001) and possible publication bias (suggested by asymmetrical funnel plots). The meta-regression showed that when tumour localisation was taken into consideration, the results were not generally significantly different, except for lung cancer trials; these showed slightly better outcomes (ratio of HRs 0.56, 95% CI 0.00 to 1.10). Randomised trials showed lesser effects on survival rates than non-randomised trials (ratio of HR 1.24, 95% CI 0.79 to 1.92). Matched-pair trials showed significantly better results than other study designs (ratio of HRs 0.33, 95% CI 0.17 to 0.65).
Iscador versus placebo (n=224 patients): There was no difference in median survival times between placebo and Iscador (one trial).
Iscador versus alternative therapies (n=912 patients; range 46 to 227): There was no significant difference in survival rates with Iscador compared with alternative therapies; this was associated with moderate heterogeneity (I2-36.6%, p=0.15). There was no indication of publication bias on the funnel plot. Results of meta-regression analyses were similar, except for randomised trials, which showed significantly worse results than non-randomised trials (ratio of HRs 3.20, 95% CI 1.16 to 8.85).
Iscador versus no treatment (n=111 patients): Iscador was associated with better survival rates than "no treatment" (HR 0.39, 95% CI 0.20 to 0.77; one trial).