Having a kid with cancer sucks. Talking to them about it sucks just as hard.
Thankfully, there are a lot of good resources out there for such conversations, including a new ebook out for the iPad:
Jack’s Diary is an interactive, illustrated story about a little boy’s courage and determination during a confusing and frightening time. The book is a colourful and engaging way to learn about cancer, treatment and getting life back to normal. Animations bring to life and add an element of fun to what can be a difficult subject to discuss with children.