Had Breast Cancer With Mastectomy. Radiation Done. Found Cyst On Ovary. Concerned For Cancer
Complex cysts usually dont mean cancer,most of them are benign and there is no need to be concerned. Considering your genetic predispostion for malignancies there is a need for detailed and repeated examinations of this cysts. It means that the most important factor which tells us about its nature is its size. Every cyst causes lower abdominal pain and irregular bleeding sometimes, malignant and benign both.
Guidelines suggest that some of image tests CT, ultrasound or laparoscopy should be done every 4-6 months to evaluate size and growth tendency of cyst. If it compress any organ around it, becomes torsioned or bleeds actively then it must be surgically removed. So just dont worry, if it shows any suspect sign it will be found in time.
Blood tests may also be helpful: especially tumor marker Ca-125 test and hormone levels. Tamoxifen can cause hormonal imbalance and benign ovarian cysts but this is not reason for stop taking it.
Hope I have answered your query. If you have any further questions I will be happy to help