Hey sweetie, I want to talk to you about something important. You know how sometimes we have to go to the doctor? Well, your brother/sister is at the hospital because they are not feeling very well. The doctors have looked at them and found something called cancer. This means that there are some bad cells in their body that are making them sick.
But don't worry! The doctors are really good at helping people feel better. They will give your brother/sister special medicine and treatments to help them get strong again. This is why Mommy and Daddy are at the hospital right now; they want to be there for your sibling and help them feel better.
I know you're missing them a lot, and that's okay to feel that way. It’s good to tell me how you feel. You can color a picture or draw something nice for your sibling to show them that you care. They will love that!
Mommy and Daddy love you very much, just like they love your brother/sister, and they will come back home as soon as they can. If you'd like, we can play together until they are back, and I can help you feel a little better too!