Some forms of cancer are ones that you live with and have to have ongoing treatment. They do not necessarily go away, but neither are they terminal
Yes, many older people have some form of cancer, but they die with it not of it. A friend's elderly mother had leukaemia. The doctor said 'this is not what she will die of' - and it wasn't.
I always admired Prince Charles's commitment to his causes, even when there was a lot of sneering, and his work with the Prince's Trust, but I've been surprised by how much I like him as King.