Chaga, ironically looking like birch cancer, has been used in centuries as a health tonic and cancer remedy in Russia and the Baltic countries. The Norwegian name for it also directly translates to something like; cancer conk.
Healthcare professionals are likely to tell you that there is not enough research done to prove that it has any effect on cancer. Well, this is to their standards of documentation. They are in reality (but not consciously) saying something like; chaga has not got same expensive studies behind it that pharmaceuticals do. Not understanding that a component that can not be patented does not lead to anyone using millions of $ on research of pure good intentions or altruism. The regulations on pharmaceuticals are extensive, and this leads to doctors setting those incredibly expensive studys as a standard that has to be met in order for them to advice any patient to use it. Not understanding that by this, they can only advice people to use patentable components.
So in short they will tell you to show caution towards a tonic used as a health drink in centuries showing 60% decrease in tumors and 25% reduction of metastasis nodules in 3 weeks in recent studies. That would be something like the same if a fireman told you to stay in bed in case of a fire because you might hurt yourself on the way out. And I'm not making this up. I just witnessed a senior doctor on a cancer hospital in Oslo giving this advice in a group on facebook.
Don't put out the fire, your hands could get burned!
Link to the in vivo mice study:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4946216/#!po=88.6667
