Sometimes I've worried about getting cancer and I've gone to the doctor for it.

IMO, there is nothing wrong with going to the doctor if you think something is wrong. Better safe than sorry. I mean, what if you assume your anxiety is acting up, but you end up having a physical ailment or disease? I'm to trying to make anyone anxious, but I'd rather throw money at doctors than assume "it's just anxiety."

That said, I'm sure therapy could help a lot. And even regular doctors can help too. Just make sure you go into a doctor's appointment and ask lots of questions. For example, if you think you have skin cancer and your dermatologist says you don't, ask, "What signs do I have to watch out for for skin cancer? Where do most skin cancer signs show up on the body? How fast does skin cancer develop? What does skin cancer look like? And what things can be confused with skin cancer?" etc etc. That can help.