I Am A60 Year Old Woman Who Has Not Had

I am a60 year old woman who has not had a period since I was about 47 years old. I never had children. I was diagnosis with DCIS breast cancer in 2012. I had a lumpectomy and 37 radiation treatments. I have been on arimadex since 2012. I recently had a pelvic ultrasound and the technician said she could'nt find my left ovary is this common with my history?