Thickened endometrium

Hi. I am a 51-year-old mom of two. My doctor just scheduled an endometrial biopsy because an internal ultrasound showed a thickened endometrium of 10.3 centimeters. I For several months I have noticed a foul-smelling light brown vaginal discharge that has required panty liners, and every once in a while I notice a thicker brown discharge that's not as light. I always just assumed those symptoms were caused by perimenopause. I wasn't concerned. Yet my doctor wanted to get ultrasound because of the discharge and my medical history: (I developed Polycystic Ovarian Syndrome at 17 or 18, and have, unfortunately, almost always been heavy.) Lately, both breasts have been extremely sore, and I have a lot of right sided pelvic pain, which I assumed was another functional cyst.  Could this be simple endometrial hyperplasia? Should I worry about endometrial cancer? My late mom died of bilateral breast cancer at the young age of 64. Thanks for any advice you can give.