evidence: One such myth is that the fungus Candida causes cancer or that cancer cells are actually a form of fungus. Research has revealed neither to be true. [...] And just to be clear: Cancer is not a fungus — this is one myth that needs to be permanently put to rest. [...] As for what causes cancer, the answer is not a fungus, but likely multiple potential causes. Doctors have found a combination of the following factors could cause cancer: