How do I tell my children?
Simply, honestly, and using the word cancer. Children usually already know something is wrong, and what they imagine is almost always worse than the truth.
Tell them three things: it is not their fault, they cannot catch it, and who will look after them. Ask your team for the social worker, because helping families do this is literally their job.
Written by two physicians. Checked against patient information from the US National Cancer Institute and Cancer Research UK.