Medical treatment is suggested by a doctor not the patient and yes you can always say no. It is never up to the patient to decide what treatment they would like, unless its deemed appropriate option by the doctor. Medical procedures are not a buffet. Even if you go to plastic surgeon, which procedures are usually due to patients request and ask for a ridiculous size breast implants many will say NO, we do not deem it safe, therefore an option. That is why many plastic surgeries are done outside of the country in places with less safety regulations. So yes there is plenty of limits to what you are allowed to do or have access to when it comes to your body.