A recent tale is that a family member got a bad cancer. Our mom called him to get the scoop, who he'll only give to her, apparently. He said 'Mom, she'll be dead in two years. She'll initially respond really well to treatment, then just get worse until the end.'
Doctors know these things, but many won't tell the patient because it's depressing, and also there's a tiny chance they're wrong.
Of course neither told said family member, and she's currently in the responding well phase. It's shattering hearing their hope, so I guess their doctor wasn't blunt either...