A century ago Rudolph Steiner developed anthroposophical medicine. It is based on intuitive thinking about associations the 4 aspects of the human body--physical, etheric, astral, and ego--and plants, minerals, and the cosmos. Steiner's intuition was based on the fact that mistletoe is a parasitic growth that eventually kills its host. Inspired by Hahnemann's "like cures like" homeopathic principle, Steiner believed that an extract of mistletoe could cure cancer.
Test tube experiments have validated Steiner's hypothesis and there are about 1000 in vitro studies showing that mistletoe extracts indeed have anticancer properties. Presently there is an NIH funded study testing this in humans at the present time.
Depending on what you read in the mainstream literature there are different opinions about the safety of mistletoe and on its effectiveness. Treatment with mistletoe for cancer is approved in Germany and insurances there reimburse for its use. There are more than 30 different preparations of mistletoe. It is used to fight cancer but also to improve quality of life.