My nephew

My nephew is my world along with his big sister. He's the happiest little three year old boy I've ever met and I'm so excited to watch him grow. Recently he was diagnosed with a cancer called Langerhans cell histiocytosis. Being the younger sibling, no one tells me much and I have a lot of questions. Does anyone know anything about LCH? Or childhood cancer in general? And does anyone have suggestions on how to help them out a bit while they go through this?