Make sure children don't feel responsible. It is important to let children know that the adult's illness is not their fault. Children dwell at the center of their small universes and often think that bad things happen because they are naughty. Opinions about this differ depending on the family's manner of handling such matters and also on the type of death involved. Some adults do not want children seeing someone they know growing weaker and losing cognizance due to medications.
Opinions also depend on what the child's relationship is with the person who has cancer.
If it is someone the child does not know very well, maybe it is less important for the young person to visit. Also, consider whether other helpful adults or older children can give special attention to the child to help with any questions and feelings. Along with these practical questions, people's ideas about whether children should be involved also are shaped by what they were told when they were little and someone died. Your opinions about including children are also shaped by how you personally cope with sadness and death. Everyone copes differently.