Problems of randomized studies in complementary medicine demonstrated in a study on mistletoe treatment of patients with breast cancer

Background: Prospective randomized studies on mistletoe therapy repeatedly demonstrated that there is a basic problem in the matter of enrolling the appropriate number of patients within a reasonable amount of time. Most studies have to face this problem. However, recent experience suggests that this problem is more pronounced in the case of mistletoe treatment of cancer patients. Objective: Possibility of recruitment and randomization of breast cancer patients for a mistletoe study. Patients: During a period of 28 months every patient was registered who was admitted to the Gynecological Hospital of the University of Heidelberg because of suspected cancer. Results: Out of 1,922 patients who were operated on for breast tumor, 521 first met the inclusion and exclusion criteria. 154 out of these 521 patients agreed to take part in the study. After availability of the final results on tumor staging and the therapy plan for conventional treatment, 80 out of the 154 women had to be excluded from the study. From the remaining 74 patients (48%), however, only 29 (39%) would have agreed to take part in a randomized mistletoe study. Conclusions: This confirms our suspicion that the difficulties of enrolment and randomization in the case of mistletoe studies exceed those of studies conducted in conventional oncology. The reasons for this dramatic effect and the possibility of alternative study designs are discussed.