A 51-year-old female visits her health care provider for vaginal bleeding and low back pain. Her health history includes anxiety disorder, type 2 diabetes, and hypertension. She is 5’2” tall and weighs 224 lbs. She smoked cigarettes for 25 years but quit 8 years ago. She is post-menopausal for over a year. What is the reason for vaginal bleeding and low back pain?