Here is one huge objection that you see of theism. That seemingly some kids die early, God must not exist.
If God exists, he wouldn’t create kids with cancer.
First off, we assume God exists. But if God exists, heaven exists. So that this life is only a pathway to the next life. It’s entirely possible that the kids with cancer go straight to heaven. Cancer then, would not be a curse but a blessing.
The second issue is the assumption that God created the kids with cancer. Of course, God created life. But he didn’t introduce death. That happened in Eden.
If we are promised a future where there is ‘no more death or mourning or crying or pain,’ where ‘God’s will is done,’ there is no cancer in heaven. There is only God’s will. And if there is only God’s will in heaven and no cancer, I think it’s fair to assume that cancer was not part of God’s will.
So why is there cancer then? How about we just cure cancer? Everybody still dies. The problem is not cancer, but death. And suffering.
So instead of asking why God caused cancer, I think it’s more important to be grateful for the time that you have. Because if it wasn’t cancer, it would be something else. And remember, your faith may protect your children.