Doctors don't!
Tell patients or parents of patients that they have cancer while they are sat in an open corridor! This is a ridiculous thing that occurs in tons of mainstream movies. Who has been to the hospital and had a doctor share personal medical information, especially that someone has cancer in full view of other people? Even when patients are examined on wards in British hospitals the doctor pulls the curtain around the bed.
If you start noticing how often this thing happens in films, I'm sure it'll irritate you too!