I’m sorry to say but you are all talking complete rubbish. I lost my wife to CANCER & btw “heart attack” which is used often is a bigger killer than cancer.
If there’s any reason for not using the word is not to scare children.
If I may go off the topic slightly if a parent ×—”ו has it the biggest חסד that can be done to the children is tell them & explain even basically what is going on. It’ll be weirder if they find out when it’s too.latr