I had a pelvic ultrasound a few days ago and my doctor rang me yesterday with the results (wasn't expecting her to but glad she did)

They found a polyp on my uterus so I'll have to get that removed. Don't know how long I'll be waiting to get that done but it will be a while I'd say

They also said they found what they think is a cyst on my left ovary. They recommended a follow up in 3 to 6 months.
My doctor wants me to go in to her next week and she said she'll do a blood test and check for an ovarian cancer marker. Of course once she said the c word I completely panicked. She told me not to be too concerned about it, that she's only doing the test to be absolutely sure. But having health anxiety, it doesn't work that way.

I'm trying really hard to stay calm but what's getting to me is that they said they think it's a cyst. They didn't say it's definitely one.
The doctor also said something about it might go away itself. I can't remember if she was talking about the polyp or the cyst at this stage. I think it was the cyst. Can that happen with them? Can they sometimes go away themselves?