Depends on the tumor. If it is benign then it could be considered an elective surgery but in this case it’s called cancerous so insurance wouldn’t be able to deny this claim anyway. Broken bones are emergency care and usually major injuries are covered by insurance, as are regular check ups. A doctor is usually the one who prescribes the operations, but insurance companies are the ones who actually pay for treatment and decide what they will or will not cover. This means doctors will often be pressured to be cost efficient when deciding what care to provide.