Immune response to cancer may cause autoimmune disorders, including anti-NMDA receptor encephalitis

Consider two seemingly unrelated medical puzzles. First: Every day, our bodies produce hundreds of billions of new cells, many of which are mutated. If cancer arises from cellular mutation, why don't we all have the disease all the time? Second: Severe autoimmune conditions like lupus and multiple sclerosis often strike without warning. No one knows what triggers them.