History of early stage breast cancer have septated ovarian cyst?

Need more details. I highly recommend you consult your oncology team and get evaluated by a gynecology oncologist. Since you are <50, it makes me concerned about a brca mutations (if you have not been tested, then get tested!). Ovarian cancer and breast cancer can be related, especially if brca is positive. If you have a estrogen positive tumor, then stopping the ovaries from making hormone may be beneficial.