My dad had a tumour taken out of his neck a week ago, plus loads of biopsy samples around the area to see what type it is. Based on initial results looks like it hasn’t spread thankfully so he may need RT and may avoid any follow up completely, depends what the biopsy says (results tomorrow)
We told his granddaughters 9,7,6 as much as we could as soon as we could, if you contact McMillan they have some child friendly books they’ll send you that you can either give to the kids to read or use to guide what you tell them.
Our situation was a bit different because we have a family friend (mum of school friends) who has late stage incurable brain cancer, and we felt we had to discuss it before particularly my eldest twigged about the lump in grandad’s neck, and got herself worried about it. So we told them the truth, that cancer is a name for a group of different types of lumps, some cancers are curable, and based on what grandad’s surgeon had said he thought this one was a treatable one. But you know your kids better than us.