Well, that is a leap for your gyn to make. Typically, ovarian cancer is a seeding cancer and this is why its not found usually until it is very advanced (and you are quite young for that, not in the usual patient population diagnosed). By seeding, I mean it starts out like the size as sand and those are tiny tumors that grow. They can easily do a CA 125 test which is a blood marker test for ovarian cancer. I'm not sure what other cancer he is talking about. Complex cysts are typically harmless. Really. Benign or non cancerous. So, I'm not sure why your doctor would say it might be cancer. Watchful waiting is what is typically protocol. They usually disappear on their own by 8 to 12 weeks and then if they don't, they may need to be removed. I'd get more info from your gyn and a second opinion before you do anything. good luck