St. John’s Wort is called by the common names of goat weed, Hypericum, witches herb, and God’s water plant. Its scientific name is Hypericum perforatum. It is usually used to treat nerve disorders, kidney failure, and headaches, but has been studied in the treatment of cancer.
One article (1) discussed St. John’s Wort and looked at its various treatment options. It has been found to increase serotonin and norepinephrine levels in the brain, which is how it treats depression.
There have been few studies on the use of St. John’s wort and the treatment of cancer and most studies have been small in design. For this reason, it is not currently being recommended routinely for the treatment of any type of cancer.
Source: 1.St. John’s Wort. https://www.mskcc.org/cancer-care/integrative-medicine/herbs/st-john-wort. Accessed 9/6/16.