Shaminism often can reduce pain and anxiety among believers. Not all shamans claim ability to cure every disease. Many select only some patients for their special type of treatment. There is good reason for this because, if a shaman fails to cure, he or she may be punished by the tribe. Shamans who know that their brand of healing will not influence the course of cancer, for example, are not likely to work with the patient with cancer.
Many shamanic cures occur in illnesses that, left alone, cure themselves in time.
The basis of shamanism is a belief that illnesses are caused by evil spirits who must be placated in order to bring about a cure. There is no scientific evidence supporting the existence of evil spirits. Like other complementary therapies, shamanism may be used in relieving certain symptoms of cancer and side effects of cancer treatment. Shamanism should not be expected to slow or reverse growth or spread of cancer.