Do doctors think it's fair to compare depression or adhd with cancer?

Yes and No: Yes! all three will destroy a person if untreated, but can be managed today. Before today's medicine, all were basically hopeless. All have an unfortunate stigma. No! today 4 of 6 cancers are cured and won't recur; the mind often must be managed lifetime. There is no point making "compare and contrast" in english class or in medicine; learn about each entity as it is.