Iscador^® is the most frequently used complementary, mistletoe cancer treatment in the world.  

Once, three quarters of a century ago, Iscador^®  was practically unknown in Europe. Since then, without promotion but with ongoing scientific investigation and refinement, it has become the most widely recognized mistletoe cancer medicine in Switzerland and Germany, where 60% of all cancer patients are now prescribed mistletoe at some point in their treatment.

Quoted from: ISCADOR: Mistletoe and Cancer Therapy