S. canadensis is called bloodroot because of the red juice found in its roots. This juice is composed mostly of sanguinarine, which is a pretty powerful toxin. Sanguinarine kills animal cells and has been known to result in serious scarring when applied to the skin and in death from ingestion. Please, do not mess about with the juice of this plant.
There are a few extremely preliminary studies which suggest the possibility that sanguinarine might be helpful in the treatment of cancer. However, these results are very preliminary indeed and DO NOT justify sanguinarine being touted as a cancer remedy; considerably more research is needed to determine if and how it could be used as a treatment for cancer. We simply do not know enough about it right now and people are more likely to do themselves harm than good trying to use sanguinarine to treat cancer. Note that S. canadensis is on the FDA list of false cancer 'cures' to be avoided.