But it is equally true that there can be no "cure for cancer" in the sense of a cure for all cancers. Just like with bipolar disorder, "cancer" is just a broad

But it is equally true that there can be no "cure for cancer" in the sense of a cure for all cancers. Just like with bipolar disorder, "cancer" is just a broad description of symptoms. There is no shared physical cause that underlies all cancers. That's why some cancers are treatable and others are still basically a death sentence. That being said, while "bipolar disorder" is clearly a disease, or like cancer, a set of diseases, it is true that the mental health profession has an unfortunate long history of making non-majority personality traits "mental illnesses" -- homosexuality was considered a mental illness until the mid 1970s, for example.