Did I do something to cause this?

Almost certainly not in the way you are imagining. Most cancers come from copying errors that build up in cells over a lifetime. They happen in people who did everything right.

Some things do raise risk, and it is fine to ask about yours. But risk is not blame, and knowing the cause changes very little about what we do next.

Written by two physicians. Checked against patient information from the US National Cancer Institute and Cancer Research UK.